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How to declare multiple Variables in JavaScript?

In this article, we will see how to declare multiple Variables in JavaScript. The variables can be declared using var , let , and const keywords. Variables are containers that store some value and they can be of any type.

These are the following ways to declare multiple variables:

Table of Content

Declaring Variables Individually

Declaring variables in a single line, using destructuring assignment.

In this case, we will declare each variable using the var, let, or const keywords.

Example: In this example, we are declaring three different variables.

You can declare multiple variables in a single line using the var, let, or const keyword followed by a comma-separated list of variable names.

Example: In this example, we are defining the three variables at once.

You can also use de-structuring assignments to declare multiple variables in one line and assign values to them.

Example: In this example, we are declaring three different variable by destructuring them at once.

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How to Declare Multiple Variables at Once in JavaScript

Table of Contents

Declaring multiple variables using commas.

Variables are a fundamental part of any programming language, especially JavaScript .

Declaring variables is how you define a variable in JavaScript that you can optionally give a value to.

In this post, we'll look at how to declare multiple variables in JavaScript.

The most common way to declare multiple variables in JavaScript is to use commas to separate the variable names.

This is the same as declaring each variable individually.

You can also initialize them with values:

You can improve readability by declaring each variable on a separate line:

Another way you can define multiple variables is by using an array:

This can be useful especially when you don't control the values of the array and want to define variables for each value.

Keep in mind that if the value of the variable is not going to change, you should use const instead of let .

In this post, we looked at how to declare multiple variables in JavaScript.

You can declare multiple variables using commas or by using an array, whichever makes the most sense for you.

Thanks for reading!

javascript assign multiple variables in one line

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Assign Multiple Variables to the Same Value in JavaScript

By James L.

Sometimes you may need to assign the same value to multiple variables. In this article, I will show you exactly how to assign the same value to multiple variables using different methods.

Method 1: Using the equal sign (=) consecutively

You can set multiple variables to the same value in JavaScript by using the equal sign (=) consecutively between the variable names and assigning a single value at the end when declaring the variables.

For example:

The above code is equivalent to

You can also declare the variables first and assign the value later.

You can also use the ‘let’ or ‘const’ keyword instead of ‘var’ to create variables.

You can also create an undeclared variable without using any keywords.

If you want to assign different values to different variables, you can also do that using the syntax below.

We can also assign different values to different variables in the same line of code.

After assigning the same value to multiple variables, if we update any of the variables, it will not affect others.

In the example below, variables a, b, and c are assigned to 10 initially and then b is changed to 20.

As you can see from the above example, only the value of variable b is changed to 20. Variables a and c are not affected when we update the value of variable b because all variables a, b, and c are assigned with a primitive value.

Variables assigned with primitive values like a number, string, boolean, bigint, undefined, symbol, and null get replaced when a new value is assigned to the same variable because primitive values are immutable. i.e. the value itself cannot be altered but the variable can be replaced. Same is not the case for non-primitive values.

You need to be very careful when assigning the same non-primitive value like array, function, and objects to multiple variables because non-primitive values are mutable. i.e. the value itself can be altered. So the value itself will be changed instead of the variable getting replaced.

If you use the equal sign (=) consecutively to create multiple variables with the same non-primitive value. If you update the value of one variable, the value of all the variables will be updated too.

As you can see from the above example that if we update the value of variable a, the value of both variables will be updated. This happens because both variables a and b points to the same array object. And if we update the value of one variable the others get affected too.

So if you want to handle them separately then you need to assign them separately.

Method 2: Using the destructuring assignment syntax

Destructuring assignment syntax is a javascript expression that helps us to unpack values from arrays or objects into different variables.

We can also assign multiple values to the same value using destructuring assignment syntax combined with the fill function.

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How to define multiple variables on a single line with JavaScript?

  • Post author By John Au-Yeung
  • Post date April 28, 2022
  • No Comments on How to define multiple variables on a single line with JavaScript?

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Sometimes, we want to define multiple variables on a single line with JavaScript.

In this article, we’ll look at how to define multiple variables on a single line with JavaScript.

To define multiple variables on a single line with JavaScript, we can use the array destructuring syntax.

For instance, we write

to assign a to 0, b to 1 , c to 2, and d` to 3 with the array destructuring syntax.

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How to declare multiple variables in JavaScript self.__wrap_n=self.__wrap_n||(self.CSS&&CSS.supports("text-wrap","balance")?1:2);self.__wrap_b=(r,n,e)=>{e=e||document.querySelector(`[data-br="${r}"]`);let o=e.parentElement,l=u=>e.style.maxWidth=u+"px";e.style.maxWidth="";let s,i=o.clientWidth,p=o.clientHeight,a=i/2-.25,d=i+.5;if(i){for(l(a),a=Math.max(e.scrollWidth,a);a+1 {self.__wrap_b(0,+e.dataset.brr,e)})).observe(o)};self.__wrap_n!=1&&self.__wrap_b(":R4p4sm:",1)

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JavaScript lets you declare multiple variables in a single statement, streamlining the process of setting up your variables. This guide dives into the syntax and strategies for declaring multiple variables efficiently in JavaScript.

Declaring multiple variables with one var keyword

The var keyword can be used to declare multiple variables at once, separated by commas. This method was commonly used in ES5 and earlier versions:

However, it's worth noting that var has function scope and is hoisted, which can lead to unexpected behaviors in certain situations.

Using let for block-scoped variables

ES6 introduced let , which allows for block-scoped variable declarations. Like var , you can declare multiple variables in one line:

Since let has block scope, it reduces the risk of errors related to variable hoisting and scope leakage.

Declaring with const for constants

When you need to declare variables whose values should not change, use const . Similar to let , you can declare multiple constants in a single line:

Remember that each constant must be initialized at the time of declaration, as their values cannot be reassigned later.

Grouping declarations and assignments

You can group variable declarations without initialization and then assign values later:

This can improve readability, especially when variable names are related or when initializing with values derived from complex expressions.

One-liner with destructuring assignment

Destructuring allows you to declare multiple variables by extracting values from arrays or objects:

For objects:

Destructuring can be especially handy for functions that return multiple values.

Default values with destructuring

When destructuring, you can also set default values for your variables in case the value extracted is undefined :

In the example above, j will default to 10 and k will be set to 21 .

Nested destructuring

For more complex data structures, nested destructuring can declare multiple variables at various levels of the structure:

This will declare n , o , and p with values 11 , 12 , and 13 respectively.

For loops and variable declarations

Within for loops, it's common to declare a loop variable, but you can declare additional variables as well:

Here, q and r are loop variables with different iteration logic.

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javascript assign multiple variables in one line

Temporal dead zone and let / const

It's important to remember that let and const declarations are subject to the Temporal Dead Zone (TDZ), meaning they cannot be accessed before declaration:

Tips for clean code

When declaring multiple variables, aim for clarity:

  • Use one let or const per variable for easier debugging and readability.
  • Group related declarations together.
  • Initialize variables with values as close to the declaration as possible.

By following these practices, you ensure that your variable declarations enhance, rather than obfuscate, the readability and maintainability of your JavaScript code.

Additional contexts for declaring variables

Using variables in different scopes.

Discuss the nuances of variable scope:

var hoisting peculiarities

Explain the behavior of var regarding hoisting:

Advanced variable declaration patterns

Chained variable assignments.

Chain variable assignments carefully:

Variables in try-catch blocks

Handle try-catch with variable scopes:

Use in modern JavaScript frameworks

Demonstrate variable declarations in frameworks:

Additional good practices

Minimizing global variables.

Limit global variables as much as possible.

Naming conventions

Adopt clear naming conventions:

Performance considerations

Consider performance in declarations:

Debugging and variable declarations

Factor in the implications on debugging when declaring variables.

Cleaning up unused variables

Regularly remove unused variables to clean up your codebase.

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How to Declare Multiple Variables in JavaScript

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  • How to Declare Multiple Variables in …

How to Declare Multiple Variables in JavaScript

Variables are containers in JavaScript that hold reusable data. They’re like cups filled with stuff that can be used repeatedly depending on how we want to use it.

Here are some JavaScript tips for declaring multiple variables.

Declare Multiple Variables in JavaScript

The most common method for declaring and initializing JavaScript variables is to write each variable on its line.

Example Code:

However, there are shorter ways to declare multiple variables in JavaScript. First, you can only use one variable keyword ( var , let , or const ) and declare variable names and values separated by commas.

The declaration above is only one line long, but it is more challenging to read than separated declarations. In addition, all variables are declared with the same keyword, let .

Other variable keywords, such as const and var, are not permitted. You can also use comma-separated declarations to create a multi-line declaration.

Finally, the de-structuring assignment can be used to reveal and preprocess multiple variables in a single line.

The array elements are extracted and assigned to the variables declared on the = operator’s left side in the code above.

The code examples above demonstrate how to declare multiple variables in a single line of JavaScript. Still, declaring variables one by one is the most common method because it separates the declaration into its line, like the following example below.

As your project grows, the code above will be the easiest to change.

When using comma-separated declaration and de-structuring assignment, you can only use one variable keyword, so you can’t change the variables from const to let without changing them all. In their own way, these variable types are distinct and help speed up code development.

However, it is recommended to use let whenever possible. You can use const whenever the variable’s value must remain constant.

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How to Declare Multiple Variables in One Line In JavaScript

How to Declare Multiple Variables in One Line In JavaScript

In JavaScript, you can declare multiple variables in one line using the comma operator or the destructuring assignment syntax. This article explores both methods and provides detailed examples to illustrate their usage.

When writing JavaScript code, it’s important to optimize efficiency and readability. One way to achieve this is by declaring multiple variables in a single line of code. This not only saves space but also allows for concise and efficient coding practices. In this article, we will explore two methods to declare multiple variables in one line: using the comma operator and employing the destructuring assignment syntax.

Table of Contents

Using the comma operator.

The comma operator in JavaScript allows you to combine multiple expressions into a single expression. When used in variable declarations, it enables you to declare multiple variables in a single line. Here’s an example:

In this example, we declare three variables a , b , and c in one line, assigning them values of 1 , 2 , and 3 , respectively. This method is particularly useful when you want to declare and initialize multiple variables simultaneously.

You can also use the comma operator to declare variables without assigning them initial values:

In this case, x , y , and z are declared but remain undefined until assigned a value later in the code.

Exploring Destructuring Assignment

Destructuring assignment is another powerful feature in JavaScript that allows you to extract values from arrays or objects into distinct variables. It also enables you to declare multiple variables in one line while assigning them values from an array or an object. Let’s take a look at some examples:

Destructuring Arrays

In this example, we declare and assign values to variables a , b , and c using array destructuring. The values 1 , 2 , and 3 are extracted from the array and assigned to the respective variables.

You can also skip elements in the array by using commas:

In this case, the value 5 is skipped and not assigned to any variable.

Destructuring Objects

Similarly, you can use destructuring assignment with objects:

Here, we declare variables firstName and lastName , extracting their values from the corresponding properties of the object.

You can also provide default values in case the property is undefined:

In this example, if the property age is not present in the object, it defaults to 25 .

Declaring multiple variables in one line can greatly enhance the efficiency and readability of your JavaScript code. In this article, we explored two methods to achieve this: using the comma operator and leveraging destructuring assignment with arrays and objects. By using these techniques appropriately, you can write concise and optimized code.

Remember, when declaring multiple variables in one line, ensure that the code remains readable and maintainable. It’s always recommended to use descriptive variable names and follow best practices to enhance the overall quality of your code.

Now that you have a solid understanding of how to declare multiple variables in one line in JavaScript, go ahead and leverage this technique to streamline your coding practices!

Happy coding!

  • MDN Web Docs: Comma Operator
  • MDN Web Docs: Destructuring Assignment

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Assigning Multiple Variables to the Same Value in JavaScript

As a JavaScript developer, you may often come across situations where you need to assign the same value to multiple variables. This can be a tedious task if you have a large number of variables to assign. However, JavaScript provides a convenient way to assign the same value to multiple variables in a single line of code. In this article, we will explore this technique and understand how it can simplify your code.

The Concept of Assigning Multiple Variables to the Same Value

In JavaScript, you can assign the same value to multiple variables by using a technique called “chaining.” This involves using the assignment operator (=) to assign a value to the first variable, and then using the same variable to assign the value to the next variable, and so on. This way, all the variables will have the same value.

In the example above, we have three variables: variable1 , variable2 , and variable3 . We assign the value 10 to all three variables in a single line of code. This is achieved by chaining the assignment operator (=) from one variable to the next.

Benefits of Assigning Multiple Variables to the Same Value

Assigning multiple variables to the same value in JavaScript offers several benefits:

  • Readability: By using this technique, you can make your code more concise and readable. Instead of repeating the same value assignment for each variable, you can assign them all in a single line.
  • Efficiency: Chaining the assignment operator reduces the number of lines of code and can improve the performance of your application.
  • Flexibility: This technique allows you to easily change the value assigned to multiple variables. Instead of modifying each assignment individually, you can simply change the value at one place.

Considerations and Best Practices

While assigning multiple variables to the same value can be a useful technique, there are a few considerations and best practices to keep in mind:

  • Order of execution: When using chaining, it’s important to understand the order of execution. The assignment is performed from right to left, so the value is assigned to the rightmost variable first.
  • Variable declaration: Make sure to declare all the variables before assigning them a value. If a variable is not declared, it will be implicitly declared in the global scope, which can lead to unexpected behavior.
  • Clarity: While concise code is desirable, it’s important to strike a balance between conciseness and clarity. If assigning multiple variables to the same value makes the code harder to understand, it may be better to assign them individually.

Assigning multiple variables to the same value in JavaScript can greatly simplify your code and improve readability. By using the chaining technique, you can assign a value to multiple variables in a single line of code. This technique offers benefits such as improved efficiency, flexibility, and readability. However, it’s important to consider the order of execution and follow best practices to ensure clarity in your code. With this knowledge, you can make your JavaScript code more concise and maintainable.

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Js versions, js functions, js html dom, js browser bom, js web apis, js vs jquery, js graphics, js examples, js references, javascript variables, variables are containers for storing data.

JavaScript Variables can be declared in 4 ways:

  • Automatically
  • Using const

In this first example, x , y , and z are undeclared variables.

They are automatically declared when first used:

It is considered good programming practice to always declare variables before use.

From the examples you can guess:

  • x stores the value 5
  • y stores the value 6
  • z stores the value 11

Example using var

The var keyword was used in all JavaScript code from 1995 to 2015.

The let and const keywords were added to JavaScript in 2015.

The var keyword should only be used in code written for older browsers.

Example using let

Example using const, mixed example.

The two variables price1 and price2 are declared with the const keyword.

These are constant values and cannot be changed.

The variable total is declared with the let keyword.

The value total can be changed.

When to Use var, let, or const?

1. Always declare variables

2. Always use const if the value should not be changed

3. Always use const if the type should not be changed (Arrays and Objects)

4. Only use let if you can't use const

5. Only use var if you MUST support old browsers.

Just Like Algebra

Just like in algebra, variables hold values:

Just like in algebra, variables are used in expressions:

From the example above, you can guess that the total is calculated to be 11.

Variables are containers for storing values.

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JavaScript Identifiers

All JavaScript variables must be identified with unique names .

These unique names are called identifiers .

Identifiers can be short names (like x and y) or more descriptive names (age, sum, totalVolume).

The general rules for constructing names for variables (unique identifiers) are:

  • Names can contain letters, digits, underscores, and dollar signs.
  • Names must begin with a letter.
  • Names can also begin with $ and _ (but we will not use it in this tutorial).
  • Names are case sensitive (y and Y are different variables).
  • Reserved words (like JavaScript keywords) cannot be used as names.

JavaScript identifiers are case-sensitive.

The Assignment Operator

In JavaScript, the equal sign ( = ) is an "assignment" operator, not an "equal to" operator.

This is different from algebra. The following does not make sense in algebra:

In JavaScript, however, it makes perfect sense: it assigns the value of x + 5 to x.

(It calculates the value of x + 5 and puts the result into x. The value of x is incremented by 5.)

The "equal to" operator is written like == in JavaScript.

JavaScript Data Types

JavaScript variables can hold numbers like 100 and text values like "John Doe".

In programming, text values are called text strings.

JavaScript can handle many types of data, but for now, just think of numbers and strings.

Strings are written inside double or single quotes. Numbers are written without quotes.

If you put a number in quotes, it will be treated as a text string.

Declaring a JavaScript Variable

Creating a variable in JavaScript is called "declaring" a variable.

You declare a JavaScript variable with the var or the let keyword:

After the declaration, the variable has no value (technically it is undefined ).

To assign a value to the variable, use the equal sign:

You can also assign a value to the variable when you declare it:

In the example below, we create a variable called carName and assign the value "Volvo" to it.

Then we "output" the value inside an HTML paragraph with id="demo":

It's a good programming practice to declare all variables at the beginning of a script.

One Statement, Many Variables

You can declare many variables in one statement.

Start the statement with let and separate the variables by comma :

A declaration can span multiple lines:

Value = undefined

In computer programs, variables are often declared without a value. The value can be something that has to be calculated, or something that will be provided later, like user input.

A variable declared without a value will have the value undefined .

The variable carName will have the value undefined after the execution of this statement:

Re-Declaring JavaScript Variables

If you re-declare a JavaScript variable declared with var , it will not lose its value.

The variable carName will still have the value "Volvo" after the execution of these statements:

You cannot re-declare a variable declared with let or const .

This will not work:

JavaScript Arithmetic

As with algebra, you can do arithmetic with JavaScript variables, using operators like = and + :

You can also add strings, but strings will be concatenated:

Also try this:

If you put a number in quotes, the rest of the numbers will be treated as strings, and concatenated.

Now try this:

JavaScript Dollar Sign $

Since JavaScript treats a dollar sign as a letter, identifiers containing $ are valid variable names:

Using the dollar sign is not very common in JavaScript, but professional programmers often use it as an alias for the main function in a JavaScript library.

In the JavaScript library jQuery, for instance, the main function $ is used to select HTML elements. In jQuery $("p"); means "select all p elements".

JavaScript Underscore (_)

Since JavaScript treats underscore as a letter, identifiers containing _ are valid variable names:

Using the underscore is not very common in JavaScript, but a convention among professional programmers is to use it as an alias for "private (hidden)" variables.

Test Yourself With Exercises

Create a variable called carName and assign the value Volvo to it.

Start the Exercise

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How to set multiple variables at once in JavaScript? [closed]

I have been setting multiple variables like this

I just read some reviewed code and both reviewers advised setting the variables in a single statement, like this:

What would be the advantage of doing it the second way? Is there a performance benefit? Is it that there is less code?

Evik James's user avatar

3 Answers 3

From a very good book called JavaScript Patterns :

Using a single var statement at the top of your functions is a useful pattern to adopt. It has the following benefits: Provides a single place to look for all the local variables needed by the function Prevents logical errors when a variable is used before it's defined Helps you remember to declare variables and therefore minimize globals Is less code (to type and to transfer over the wire)

The author also recommends initializing the variables when you declare them when possible.

Ryan Miller's user avatar

  • \$\begingroup\$ Those are some compelling reasons, the least of which is a performance boost. \$\endgroup\$ –  Evik James Commented Jun 12, 2012 at 21:10
  • \$\begingroup\$ @Evik - mucking up the global namespace, by forgetting the var keyword can have huge performance impacts. So, I assume you are referring to the "is less code" bullet. \$\endgroup\$ –  Ryan Miller Commented Jun 12, 2012 at 21:13
  • \$\begingroup\$ I tend to not mistakes like that, forgetting to var it. I made that mistake early on and killed my browser memory doing a bunch of Ajax stuff. Assuming I code it correctly, it will have little performance advantage. The real advantage will be in creating the necessary local variables right away at the top of the function. \$\endgroup\$ –  Evik James Commented Jun 12, 2012 at 21:24
  • \$\begingroup\$ I'd argue that at least #1 and #3 do not matter in this case. The first code example does provide a "single place to look for" and minimizes globals just as much as the second example. In fact, the only example of those 4 that seems to make a difference in this case is #4 and, even then, not by much(in this particular case - assuming spaces are used - there are exactly as many bytes being sent) \$\endgroup\$ –  luiscubal Commented Jun 12, 2012 at 22:42

In terms of performance, there is little difference across both methods. Another test found here which has greater browser coverage.

In terms of readability, I'd go for the multiple variables using a single var since it is less messy.

All in all, it depends on you.

Joseph's user avatar

There should be no noticeable difference in performance (even if there was, it would most likely be negligible) and they mean the same.

It's just a matter of picking the one that's most readable. Frankly, I don't find the second example more readable than the first, but this is subjective.

EDIT: One possible difference is that smaller code (assuming those are charaters replacing "var" are tabs and not spaces) might reduce traffic, making the page faster. However, in practice, I think the best JS minifiers should handle that sort of thing for you.

luiscubal's user avatar

  • \$\begingroup\$ I think you meant "there should be NO noticeable..." Is that correct? \$\endgroup\$ –  Evik James Commented Jun 12, 2012 at 21:05
  • \$\begingroup\$ @EvikJames Indeed. Sorry for the mistake. \$\endgroup\$ –  luiscubal Commented Jun 12, 2012 at 21:06

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javascript assign multiple variables in one line

Multiple variable assignment with Javascript

Assigning multiple variables.

Using the same set sort of examples as in the PHP post, but this time with Javascript, multiple variables can be assigned by using = multiple times on the same line of code like so:

Any subsequent updates to any of the variables will not affect the other assigned variables. In the next example a, b and c are again initialised with "AAA" and then b is changed to "BBB".

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Matthew Tyson

User-defined variables in JavaScript

Javascript variables hold a wide variety of information and can be used with virtually any data type. here's how to use variables to store numbers, text strings, objects, and more..

A young developer coding; programming, creative, ideas

Without variables, programming languages are next to useless. Fortunately, JavaScript’s variable system is incredibly powerful and versatile. This article shows you how to use JavaScript variables to store numbers, text strings, objects, and other data types. Once you’ve stored this information, you can use it anywhere in your program.

All about JavaScript variables

Here’s what you’ll learn in this article:

What is a user-defined variable in JavaScript?

Data types in javascript variables, how to create javascript variables, how to store data types in javascript variables, tips for naming javascript variables, dynamic typing and javascript variables.

  • How to work with string variables

What you need to know about variable scope

All JavaScript programming happens in an environment like a web browser, Node, or Bun.js. Each of these environments has its own set of pre-defined variables like window and console . These variables are not user-defined because they are set by the environment. Another kind of variable is the user-defined variable defined by other developers, such as in third-party frameworks or libraries you use. Then there are variables you create while writing your programs, using the let and const keywords. These are defined by you, the user. This article is about how to create your own user-defined variables.

Variables hold a wide variety of information temporarily. The JavaScript data types that can be stored in a variable include:

  • Numeric values, or “numbers”: Variables hold numbers, which can be used in simple or complex mathematical computations. Example: 2 + 2 = 4.
  • Character strings: A string is a collection of text, such as “JavaScript” or “My name is Mudd.”
  • True/False values: The Boolean data type, which has only values of true or false.
  • Objects: Variables can hold JavaScript objects or user-defined objects.

JavaScript variables can hold a few other kinds of data, but these are by far the most commonly used types.

Several JavaScript instructions are used to create variables, but the most basic way to create a variable manually is with the equals ( = ) assignment operator:

The first argument is the name of the variable. Variable names can be very long, but there are restrictions on the characters you can use. We’ll discuss these in detail soon.

In practice, variables should be declared using either the let or const statements:

Both let and const restrict the visibility of the variable to the current code block. The const statement creates a “constant” variable, which cannot be changed. When possible, use const for cleaner code.

The second argument is the variable’s content. You can put all sorts of data into a variable, including a number, a string, a math expression (such as 2 + 2), and various other things. In JavaScript, variables are dynamically typed, so the same variable can hold any kind of data.

Let’s take a look at how to store the most common data types in JavaScript variables.

Storing numbers in JavaScript variables

A number is one or more digits stored in the computer in such a way that JavaScript can perform mathematical calculations with them. JavaScript supports both integers and floating-point values. To place a number in a variable, just provide the variable name, the equals sign ( aka the variable assignment operator), and the value you want to use. For example, the following code places the number 10 in a variable named myVar :

JavaScript makes it easy to deal with numbers. You can freely mix and match floats. For example, myVar = 10 * .3 is okay.

Storing strings in JavaScript variables

A string is one or more text characters arranged in memory in a single-file fashion. Strings can contain numbers (digits), letters, punctuation, or a combination of these. You cannot perform math calculations on strings (it will return NaN if you try, for Not a Number). Strings are assigned to JavaScript variables by being enclosed in a set of quotes, which can be single or double:

Unlike some languages, JavaScript makes no distinction between the two forms of quotation marks. Here is an example of how to place a string into a variable:

Storing Boolean values in JavaScript variables

There are only two Boolean values: true or false. Some programming languages don’t have a separate set of Boolean values; instead, they use 0 for false, and 1 or -1 (or any other non-zero value) for true. JavaScript lets you use these numbers to represent true and false but, in addition, reserves the words true and false to refer to the Boolean true and false values.

You can think of the Boolean true/false values as being equivalent to on/off or yes/no. To assign a Boolean value to a variable, enter the word true or false without quotes. Here’s an example:

JavaScript “coerces” variables to Boolean when testing to true/false. Additionally, a variety of “falsy” and “truthy” variables exist in this vein. We’ve mentioned 0 and 1, which naturally map to false and true. In fact, any number other than 0 is coerced to true. Another coerced value is the empty string (false) and a string holding a value (true):

Another common use is to establish the falseness of undefined and null :

Storing objects in JavaScript variables

Variables can contain objects , which are containers for other values and are incredibly useful in many scenarios. There are two kinds of object variables in JavaScript:

  • Variables that contain built-in browser-related objects—window, document, and so on. These are references to objects you did not create. They are like copies, but the copies change if the original changes. In some cases, changing the object in the variable affects the original JavaScript object.
  • Variables that contain user-defined objects represent the actual object. A change to the object in the variable changes only that object.

To assign a JavaScript object to a variable, provide the name of the object, as in:

To assign a new copy of a user-defined object to a variable, use the new statement and provide the name of the object function:

Or, you could use an object literal:

JavaScript offers a great deal of latitude when it comes to naming variables. JavaScript variable names can be almost unlimited in length, although for practical reasons you’ll probably want to keep your variable names under 10 or 15 characters. Shorter variable names are easier to type and remember.

Here are more tips to keep in mind when naming your variables:

  • Variable names should consist of letters only, without spaces. You can use numbers as long as the name doesn’t start with a digit. For example, myVar1 is okay but 1MyVar is not.
  • Don’t use punctuation characters in variable names, with one xception: the underscore character ( _ ). So, the variable my_Var is okay, but my*Var is not. Variables can begin with the underscore character.
  • Variable names are case sensitive. The variable MyVar is considered not the same variable as myVar , myVar , and other variations.
  • It is conventional to use camelCase for JavaScript variable names, for example:  thisIsMyVariable .
  • Avoid obscure abbreviations. An abbreviation like msg is okay because most people know it is short for “message.” Less common abbreviations should be avoided.

Unlike some other programming languages, JavaScript does not require you to explicitly define the type of variable you want to create. This JavaScript behavior is sometimes called loose data typing , more formally known as dynamic or weak typing. JavaScript’s loose data typing differs from C and Java, which both use strict data typing.

What this means is that in JavaScript, you don’t need to declare a variable type. JavaScript will happily use the same variable for numbers, strings, and objects. (Part of TypeScript’s power is that it adds a strongly typed layer on top of JavaScript .) 

Assigning variables with let and const

Good JavaScript uses the let and const keywords to declare variables. Here’s an example:

You’ll still see var in some older code. If possible, refactor it to use let . (Though doing that is sometimes not straightforward if the variable is used as a global.) You’ll also see variables declared without a keyword declaration—for instance, myVar = “foo” . That’s just bad style!

You can also use the let statement with a variable name to declare the variable but not define a value for it:

In this case, you’ve defined myVar in memory but have yet to assign a value to it. Later, you will be able to use the variable.

Working with string variable limits

String variable limits were once a common problem in front-end JavaScript. These days, the limit on how long a JavaScript string variable can be is dependent on the engine you are running in—whether it be Chrome, Edge, Node, Bun, etc. In general, you won’t run into problems with string variable limits.

You can create longer strings by “piecing” them together. After assigning a string to each variable, you combine them using the plus ( + ) character. This is called concatenation . The following example shows how concatenation works:

You can also use interpolation , which makes it easier to incorporate variables into a string:

The scope of a variable has nothing to do with optics or mouthwash, but rather the extent to which a variable is visible to other parts of a JavaScript program. In the old days, var would hoist a variable to the top of the scope. In modern JavaScript, let and const behave more in line with other languages, keeping the variable within the current code block. The current block is encompassed by curly braces, as shown here:

In this example, the console will output “bar”.  The foo defined inside the if block is held within that block. Global variables are a common source of logic errors, so keeping a variable in the smallest scope is always good practice.

Although variables are a fairly simple aspect of JavaScript, they are also universal and essential. Knowing how to work with them is like mastering the basic moves of a martial art: practice pays off. You never really leave the basics behind; you just get better at making them work for you.

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Matthew Tyson

Matthew Tyson is a founder of Dark Horse Group, Inc. He believes in people-first technology. When not playing guitar, Matt explores the backcountry and the philosophical hinterlands. He has written for JavaWorld since 2007.

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How to assign a multiline string literal to a variable?

How do I convert this Ruby code with a multiline string into JavaScript?

Heretic Monkey's user avatar

43 Answers 43

ECMAScript 6 (ES6) introduces a new type of literal, namely template literals . They have many features, variable interpolation among others, but most importantly for this question, they can be multiline.

A template literal is delimited by backticks :

(Note: I'm not advocating to use HTML in strings)

Browser support is OK , but you can use transpilers to be more compatible.

Original ES5 answer:

Javascript doesn't have a here-document syntax. You can escape the literal newline, however, which comes close:

sodimel's user avatar

  • 283 Be warned: some browsers will insert newlines at the continuance, some will not. –  staticsan Commented Apr 30, 2009 at 2:22
  • 45 Visual Studio 2010 seems to be confused by this syntax as well. –  jcollum Commented Apr 17, 2011 at 21:58
  • 63 @Nate It is specified in ECMA-262 5th Edition section 7.8.4 and called LineContinuation : "A line terminator character cannot appear in a string literal, except as part of a LineContinuation to produce the empty character sequence. The correct way to cause a line terminator character to be part of the String value of a string literal is to use an escape sequence such as \n or \u000A." –  some Commented Sep 25, 2012 at 2:28
  • 24 I don't see why you'd do this when browsers treat it inconsistently. "line1\n" + "line2" across multiple lines is readable enough and you're guaranteed consistent behavior. –  SamStephens Commented Mar 20, 2013 at 20:14
  • 25 "Browser support is OK"... not supported by IE11 - not OK –  Tom Andraszek Commented May 25, 2017 at 5:18

ES6 Update:

As the first answer mentions, with ES6/Babel, you can now create multi-line strings simply by using backticks:

Interpolating variables is a popular new feature that comes with back-tick delimited strings:

This just transpiles down to concatenation:

Google's JavaScript style guide recommends to use string concatenation instead of escaping newlines: Do not do this: var myString = 'A rather long string of English text, an error message \ actually that just keeps going and going -- an error \ message to make the Energizer bunny blush (right through \ those Schwarzenegger shades)! Where was I? Oh yes, \ you\'ve got an error and all the extraneous whitespace is \ just gravy. Have a nice day.'; The whitespace at the beginning of each line can't be safely stripped at compile time; whitespace after the slash will result in tricky errors; and while most script engines support this, it is not part of ECMAScript. Use string concatenation instead: var myString = 'A rather long string of English text, an error message ' + 'actually that just keeps going and going -- an error ' + 'message to make the Energizer bunny blush (right through ' + 'those Schwarzenegger shades)! Where was I? Oh yes, ' + 'you\'ve got an error and all the extraneous whitespace is ' + 'just gravy. Have a nice day.';

Devin Rhode's user avatar

  • 30 I don't understand Google's recommendation. All browsers except extremely old ones support the backslash followed by newline approach, and will continue to do so in the future for backward compatibility. The only time you'd need to avoid it is if you needed to be sure that one and only one newline (or no newline) was added at the end of each line (see also my comment on the accepted answer). –  Matt Browne Commented Feb 26, 2013 at 18:40
  • 8 Note that template strings aren't supported in IE11, Firefox 31, Chrome 35, or Safari 7. See kangax.github.io/compat-table/es6 –  EricP Commented May 24, 2014 at 2:41
  • 46 @MattBrowne Google's recommendation is already documented by them, in order of importance of reasons: (1) The whitespace at the beginning of each line [in the example, you don't want that whitespace in your string but it looks nicer in the code] (2) whitespace after the slash will result in tricky errors [if you end a line with \ instead of `\` it's hard to notice] and (3) while most script engines support this, it is not part of ECMAScript [i.e. why use nonstandard features?] Remember it's a style guide, which is about making code easy to read+maintain+debug: not just "it works" correct. –  ShreevatsaR Commented Jul 31, 2016 at 20:29
  • 3 amazing that after all these years string concatenation is still the best/safest/most compliant way to go with this. template literals (above answer) don't work in IE and escaping lines is just a mess that you're soon going to regret –  Tiago Duarte Commented Nov 11, 2016 at 12:31
  • 3 Found out the hard way that older versions of Android do not support the backticks so if you have an Android app using the webView your backticks cause your app to not run! –  Michael Fever Commented Jun 26, 2019 at 19:45

the pattern text = <<"HERE" This Is A Multiline String HERE is not available in js (I remember using it much in my good old Perl days).

To keep oversight with complex or long multiline strings I sometimes use an array pattern:

or the pattern anonymous already showed (escape newline), which can be an ugly block in your code:

Here's another weird but working 'trick' 1 :

external edit: jsfiddle

ES20xx supports spanning strings over multiple lines using template strings :

1 Note: this will be lost after minifying/obfuscating your code

KooiInc's user avatar

  • 40 Please don't use the array pattern. It will be slower than plain-old string concatenation in most cases. –  BMiner Commented Jul 17, 2011 at 12:39
  • 86 The array pattern is more readable and the performance loss for an application is often negligible. As that perf test shows, even IE7 can do tens of thousands of operations per second. –  Benjamin Atkin Commented Aug 20, 2011 at 8:16
  • 23 +1 for an elegant alternative that not only works the same way in all browsers, but is also future-proof. –  Pavel Commented May 21, 2012 at 6:06
  • 28 @KooiInc Your tests start with the array already created, that skews the results. If you add the initialization of the array, straight concatenation is faster jsperf.com/string-concat-without-sringbuilder/7 See stackoverflow.com/questions/51185/… As a trick for newlines, it may be OK, but it's definitely doing more work than it should –  Ruan Mendes Commented Aug 4, 2013 at 8:02
  • 12 @BMiner: 1) "Premature optimization is the root of all evil" - Donald Knuth, and 2) 'readability' is in the eye of the beholder –  user2418182 Commented Mar 25, 2014 at 15:27

You can have multiline strings in pure JavaScript.

This method is based on the serialization of functions, which is defined to be implementation-dependent . It does work in the most browsers (see below), but there's no guarantee that it will still work in the future, so do not rely on it.

Using the following function:

You can have here-documents like this:

The method has successfully been tested in the following browsers (not mentioned = not tested):

  • Opera 9.50 - 12 (not in 9-)
  • Safari 4 - 6 (not in 3-)
  • Chrome 1 - 45
  • Firefox 17 - 21 ( not in 16- )
  • Rekonq 0.7.0 - 0.8.0
  • Not supported in Konqueror 4.7.4

Be careful with your minifier, though. It tends to remove comments. For the YUI compressor , a comment starting with /*! (like the one I used) will be preserved.

I think a real solution would be to use CoffeeScript .

ES6 UPDATE: You could use backtick instead of creating a function with a comment and running toString on the comment. The regex would need to be updated to only strip spaces. You could also have a string prototype method for doing this:

Someone should write this .removeIndentation string method... ;)

gpl's user avatar

  • 287 What!? creating and decompiling a Function to hack a multiline comment into being a multiline string? Now that's ugly. –  fforw Commented Jun 17, 2011 at 15:49
  • 5 jsfiddle.net/fqpwf works in Chrome 13 and IE8/9, but not FF6. I hate to say it, but I like it, and if it could be an intentional feature of each browser (so that it wouldn't disappear), I'd use it. –  Jason Kleban Commented Sep 9, 2011 at 21:36
  • 3 @uosɐſ: for it to be intentional, it'd have to be in the spec; or so widespread used, that browser makers wouldn't want to remove this "accidental" feature. Thanks for the experiments though... Try some coffeescript. –  Jordão Commented Sep 10, 2011 at 2:37
  • 2 a.toString().substring(15, a.toString().length-4) also works, and doesn't need to scan the entire string (although it most likely will and the counting makes it another scan anyway. Oh wel.) –  Lodewijk Commented Jan 8, 2012 at 23:53
  • 3 Extremely handy. I'm using it for (Jasmine) unit tests, but avoiding it for production code. –  Jason Commented Jul 13, 2012 at 5:23

You can do this...

  • First example is great and simple. Much better than the \ approach as I'm not sure how browser's would handle the backslash as an escape character and as a multi-line character. –  Matt K Commented Nov 3, 2011 at 19:13
  • The CDATA code (E4X) is obsolete and will soon stop working even in Firefox . –  Brock Adams Commented Nov 22, 2012 at 12:16
  • e4x.js would be the good future-proof solution –  Paul Sweatte Commented Jan 19, 2013 at 2:54

I came up with this very jimmy rigged method of a multi lined string. Since converting a function into a string also returns any comments inside the function you can use the comments as your string using a multilined comment /**/. You just have to trim off the ends and you have your string.

Luke's user avatar

  • 50 This is absolutely terrifying. I love it (although you may need to do a regex match because I'm not sure how precise the whitespace for toString() is. –  Kevin Cox Commented Apr 7, 2013 at 21:53
  • 2 This solution does not seem to work in firefox, maybe it's a security feature for the browser? EDIT: Nevermind, it only does not work for Firefox Version 16. –  Bill Software Engineer Commented Jun 6, 2013 at 19:18
  • 59 Also beware of minifiers that strip comments... :D –  jondavidjohn Commented Oct 22, 2013 at 19:07
  • 9 This is why we can't have nice things. –  Danilo M. Oliveira Commented Oct 15, 2018 at 18:39
  • 8 You can do some weird stuff in javascript land. Though in all honesty, you should never use this. –  Luke Commented Oct 25, 2018 at 23:25

I'm surprised I didn't see this, because it works everywhere I've tested it and is very useful for e.g. templates:

Does anybody know of an environment where there is HTML but it doesn't work?

Peter V. Mørch's user avatar

  • 25 Anywhere you don't want to put your strings into seperate and distant script elements. –  Lodewijk Commented Jan 9, 2012 at 1:12
  • 10 A valid objection! It isn't perfect. But for templates, that separation is not only ok, but perhaps even encouraged. –  Peter V. Mørch Commented Feb 3, 2012 at 9:03
  • 2 I prefer splitting everything over 80/120 characters into multiline, I'm afraid that's more than just templates. I now prefer 'line1 ' + 'line2' syntax. It's also the fastest (although this might rival it for really large texts). It's a nice trick though. –  Lodewijk Commented Feb 3, 2012 at 22:51
  • 29 actually, this is HTML not Javascript :-/ –  CpILL Commented May 22, 2012 at 8:54
  • 6 however, the task of obtaining a multiline string in javascript can be done this way –  Davi Fiamenghi Commented Jul 30, 2013 at 21:41

I solved this by outputting a div, making it hidden, and calling the div id by jQuery when I needed it.

Then when I need to get the string, I just use the following jQuery:

Which returns my text on multiple lines. If I call

enter image description here

  • 4 Thanks for this! It's the only answer I've found that solves my problem, which involves unknown strings that may contain any combination of single and double quotes being directly inserted into the code with no opportunity for pre-encoding. (it's coming from a templating language that creates the JS -- still from a trusted source and not a form submission, so it's not TOTALLY demented). –  octern Commented Jun 23, 2013 at 17:19
  • This was the only method that actually worked for me to create a multi-line javascript string variable from a Java String. –  beginner_ Commented Aug 6, 2013 at 12:06
  • 4 What if the string is HTML? –  Dan Dascalescu Commented Jan 24, 2014 at 8:39
  • 4 $('#UniqueID').content() –  mplungjan Commented Jan 24, 2014 at 9:28
  • 1 @Pacerier Everything I've read, from Google as well as other sites, says that nowadays Google does index display:none content, most likely due to the popularity of JavaScript-styled front-ends. (For example, an FAQ page with hide/show functionality.) You need to be careful though, because Google says they can punish you if the hidden content appears to be designed to artificially inflate your SEO rankings. –  Gavin Commented Aug 8, 2017 at 13:12

There are multiple ways to achieve this

1. Slash concatenation

2. regular concatenation

3. Array Join concatenation

Performance wise, Slash concatenation (first one) is the fastest.

Refer this test case for more details regarding the performance

With the ES2015 , we can take advantage of its Template strings feature. With it, we just need to use back-ticks for creating multi line strings

Vignesh Subramanian's user avatar

  • 11 I think it's that you've just regurgitated what has already on the page for five years, but in a cleaner way. –  RandomInsano Commented Aug 2, 2014 at 18:22
  • won't slash concatenation also include the whitespace in beginning of lines? –  f.khantsis Commented May 9, 2017 at 23:39

Using script tags:

  • add a <script>...</script> block containing your multiline text into head tag;

get your multiline text as is... (watch out for text encoding: UTF-8, ASCII)

jpfreire's user avatar

  • I think this strategy is clean & far underused. jsrender uses this. –  xdhmoore Commented Jan 9, 2015 at 15:57
  • I'm using this with innerText iso innerHTML, But how do I make sure that the whitespaces are preserved ? –  David Nouls Commented Jul 16, 2015 at 8:53
  • Also ajax queries in case you are using them. You can try to change your headers xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); I don't remember having other problems than mistyping comments in JS. Spaces where no problems. –  jpfreire Commented Oct 28, 2015 at 5:40

A simple way to print multiline strings in JavaScript is by using template literals(template strings) denoted by backticks (` `). you can also use variables inside a template string-like (` name is ${value} `)

You can also

const value = `multiline` const text = `This is a ${value} string in js`; console.log(text);

itsankitbhusal's user avatar

I like this syntax and indendation:

(but actually can't be considered as multiline string)

semente's user avatar

  • 3 I use this, except I put the '+' at the end of the preceding line, to make it clear the statement is continued on the next line. Your way does line up the indents more evenly though. –  Sean Commented Oct 4, 2012 at 8:54
  • @Sean i use this too, and i still prefer put the '+' at the beginning of each new line added, and the final ';' on a new line, cuz i found it more 'correct'. –  AgelessEssence Commented Nov 14, 2013 at 5:06
  • 7 putting the + at the beginning allows one to comment out that line without having to edit other lines when its the first/last line of the sequence. –  moliad Commented Dec 12, 2013 at 15:38
  • 3 I prefer the + at the front too as visually I do not need to scan to the end of the line to know the next one is a continuation. –  Daniel Sokolowski Commented May 7, 2014 at 15:40

Downvoters : This code is supplied for information only.

This has been tested in Fx 19 and Chrome 24 on Mac

var new_comment; /*<<<EOF <li class="photobooth-comment"> <span class="username"> <a href="#">You</a>: </span> <span class="comment-text"> $text </span> @<span class="comment-time"> 2d </span> ago </li> EOF*/ // note the script tag here is hardcoded as the FIRST tag new_comment=document.currentScript.innerHTML.split("EOF")[1]; document.querySelector("ul").innerHTML=new_comment.replace('$text','This is a dynamically created text'); <ul></ul>

mplungjan's user avatar

  • 17 That's horrific. +1. And you can use document.currentScript instead of getElement... –  Orwellophile Commented May 27, 2015 at 10:00
  • 1 Undefined "you" in chrome for osx –  mplungjan Commented May 27, 2015 at 16:46
  • 1 jsfiddle-fixed - I must have had "you" defined globally in my console. Works now (chrome/osx). The nice thing about adding the comment to a var is that you're not in a function context, jsfiddle-function-heredoc although the function thing would be cool for class methods. might be better to pass it a replace { this: that } object anyways. fun to push something crazy to the limit anyway :) –  Orwellophile Commented Jun 1, 2015 at 16:44
  • 1 Forget the haters. This is the only correct answer bar ES6. All the other answers require concatenation, computation of some sort, or escaping. This is actually pretty cool and I'm going to use it as a way to add documentation to a game I'm working on as a hobby. As long as this trick isn't used for anything that could invoke a bug (I can see how someone would go "Semicolon, derp. Lets put the comment on the next line." and then it breaks your code.) But, is that really a big deal in my hobby game? No, and I can use the cool trick for something useful. Great answer. –  Thomas Dignan Commented Jul 27, 2015 at 21:10
  • 2 I've never been brave enough to use this technique in production code, but where I DO use it a lot is in unit testing, where often it's easiest to dump the value of some structure as a (quite long) string and compare it to what it 'should' be. –  Ben McIntyre Commented Feb 3, 2016 at 0:00

There's this library that makes it beautiful:

https://github.com/sindresorhus/multiline

Shahar 'Dawn' Or's user avatar

  • 1 This support in nodejs , using in browser must becareful. –  Huei Tan Commented May 5, 2014 at 8:52
  • 3 @HueiTan Docs state it also works in the browser. Which makes sense - it's just Function.prototype.String() . –  mikemaccana Commented Jul 13, 2014 at 19:14
  • ya but it said "While it does work fine in the browser, it's mainly intended for use in Node.js. Use at your own risk.While it does work fine in the browser, it's mainly intended for use in Node.js. Use at your own risk." (Just becareful XD) –  Huei Tan Commented Jul 14, 2014 at 9:37
  • @HueiTanYep I read that part. But Function.prototype.toString() is pretty stable and well known. –  mikemaccana Commented Jul 14, 2014 at 10:52
  • 1 Best answer for me because it at least achieves multiline without all the rubbish in the middle(The rubbish at the beginning and ends I can deal with). –  Damien Golding Commented Aug 27, 2014 at 6:25

Found a lot of over engineered answers here. The two best answers in my opinion were:

which eventually logs:

That logs it correctly but it's ugly in the script file if str is nested inside functions / objects etc...:

My really simple answer with regex which logs the str correctly:

Please note that it is not the perfect solution but it works if you are sure that after the new line (\n) at least one space will come (+ means at least one occurrence). It also will work with * (zero or more).

You can be more explicit and use {n,} which means at least n occurrences.

Niv's user avatar

  • 7 Why wouldn't you just [ "line", "line2", "line3" ].join("\n") . –  Kaz Commented Jan 21, 2022 at 19:18

The equivalent in javascript is:

Here's the specification . See browser support at the bottom of this page . Here are some examples too.

Lonnie Best's user avatar

Ruby produce : "This\nIs\nA\nMultiline\nString\n" - below JS produce exact same string

text = `This Is A Multiline String ` // TEST console.log(JSON.stringify(text)); console.log(text);

This is improvement to Lonnie Best answer because new-line characters in his answer are not exactly the same positions as in ruby output

Kamil Kiełczewski's user avatar

  • text is string why json.stringify? –  FlatLander Commented Jul 12, 2020 at 11:20
  • 1 @FlatLander this is only for test - to see where are exactly new-line characters \n (to compare with ruby output (working example linked in answer) ) - this is improvement of Lonnie answer because new-line characters in his answer are not exactly the same positions as in ruby output –  Kamil Kiełczewski Commented Jul 12, 2020 at 20:51

This works in IE, Safari, Chrome and Firefox:

stillatmycomputer's user avatar

  • 8 Just think about it. Do you think it's valid? Don't you think it can cause display problems? –  Sk8erPeter Commented Feb 24, 2012 at 1:55
  • 6 Why the downvotes? This is a creative answer, if not very practical! –  dotancohen Commented Feb 29, 2012 at 2:32
  • 3 no, it's not. One should rather use templates: $.tmpl() ( api.jquery.com/tmpl ), or EJS ( embeddedjs.com/getting_started.html ), etc. One reason for downvotes is that it's really far from a valid code and using this can cause huge display problems. –  Sk8erPeter Commented Mar 24, 2012 at 0:07
  • I hope no one ever uses this answer in practice, but it's a neat idea –  DCShannon Commented Mar 13, 2015 at 23:48
  • Edge case when you have ' within the html. in that case you may have to use html entities &#39; . –  borracciaBlu Commented Dec 18, 2020 at 4:25

to sum up, I have tried 2 approaches listed here in user javascript programming (Opera 11.01):

  • this one didn't work: Creating multiline strings in JavaScript
  • this worked fairly well, I have also figured out how to make it look good in Notepad++ source view: Creating multiline strings in JavaScript

So I recommend the working approach for Opera user JS users. Unlike what the author was saying:

It doesn't work on firefox or opera; only on IE, chrome and safari.

It DOES work in Opera 11. At least in user JS scripts. Too bad I can't comment on individual answers or upvote the answer, I'd do it immediately. If possible, someone with higher privileges please do it for me.

Community's user avatar

  • This is my first actual comment. I have gained the upvote privilege 2 days ago so so I immediately upvoted the one answer I mentioned above. Thank you to anyone who did upvote my feeble attempt to help. –  Tyler Commented Jul 24, 2011 at 12:34
  • Thanks to everyone who actually upvoted this answer: I have now enough privileges to post normal comments! So thanks again. –  Tyler Commented Aug 31, 2012 at 2:41

My extension to https://stackoverflow.com/a/15558082/80404 . It expects comment in a form /*! any multiline comment */ where symbol ! is used to prevent removing by minification (at least for YUI compressor)

pocheptsov's user avatar

Updated for 2015 : it's six years later now: most people use a module loader, and the main module systems each have ways of loading templates. It's not inline, but the most common type of multiline string are templates, and templates should generally be kept out of JS anyway .

require.js: 'require text'.

Using require.js 'text' plugin , with a multiline template in template.html

NPM/browserify: the 'brfs' module

Browserify uses a 'brfs' module to load text files. This will actually build your template into your bundled HTML.

mikemaccana's user avatar

If you're willing to use the escaped newlines, they can be used nicely . It looks like a document with a page border .

enter image description here

  • 3 Wouldn't this add extraneous blank spaces? –  tomByrer Commented Dec 6, 2015 at 12:29
  • 1 @tomByrer Yes, good observation. It's only good for strings which you don't care about white space, e.g. HTML. –  seo Commented Dec 6, 2015 at 23:02

Easiest way to make multiline strings in Javascrips is with the use of backticks ( `` ). This allows you to create multiline strings in which you can insert variables with ${variableName} .

let name = 'Willem'; let age = 26; let multilineString = ` my name is: ${name} my age is: ${age} `; console.log(multilineString);

compatibility :

  • It was introduces in ES6 // es2015
  • It is now natively supported by all major browser vendors (except internet explorer)

Check exact compatibility in Mozilla docs here

Willem van der Veen's user avatar

  • Is this now compatible with all recent browsers? Or are there some browsers which still do not support this syntax? –  cmpreshn Commented Sep 28, 2018 at 3:37
  • Sorry for my extreme late comment, edited the answer added compatibility info ;) –  Willem van der Veen Commented Oct 1, 2018 at 21:28

The ES6 way of doing it would be by using template literals:

More reference here

jenil christo's user avatar

  • This answer is not only small, incomplete and bad formatted, but also doesn't add absolutely anything to the previous answers. Flagging it and hopping to be deleted. –  Victor Schröder Commented Jan 18, 2019 at 17:43

You can use TypeScript (JavaScript SuperSet), it supports multiline strings, and transpiles back down to pure JavaScript without overhead:

If you'd want to accomplish the same with plain JavaScript:

Note that the iPad/Safari does not support 'functionName.toString()'

If you have a lot of legacy code, you can also use the plain JavaScript variant in TypeScript (for cleanup purposes):

and you can use the multiline-string object from the plain JavaScript variant, where you put the templates into another file (which you can merge in the bundle).

You can try TypeScript at http://www.typescriptlang.org/Playground

Stefan Steiger's user avatar

  • Any documentation on the iPad/Safari limitation? MDN seems to think it's all good - developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… –  Campbeln Commented Aug 5, 2017 at 18:15
  • @Campbeln: CoWorker told me this (he used the code). Haven't tested it myselfs. Might also depend on the iPad/Safari version - so probably depends. –  Stefan Steiger Commented Aug 6, 2017 at 16:07

ES6 allows you to use a backtick to specify a string on multiple lines. It's called a Template Literal. Like this:

Using the backtick works in NodeJS, and it's supported by Chrome, Firefox, Edge, Safari, and Opera.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals

earl3s's user avatar

You can use tagged templates to make sure you get the desired output.

For example:

Pedro Andrade's user avatar

Also do note that, when extending string over multiple lines using forward backslash at end of each line, any extra characters (mostly spaces, tabs and comments added by mistake) after forward backslash will cause unexpected character error, which i took an hour to find out

Prakash GPz's user avatar

Please for the love of the internet use string concatenation and opt not to use ES6 solutions for this. ES6 is NOT supported all across the board, much like CSS3 and certain browsers being slow to adapt to the CSS3 movement. Use plain ol' JavaScript, your end users will thank you.

var str = "This world is neither flat nor round. "+ "Once was lost will be found";

Pragmatiq's user avatar

  • 3 while i agree with your point, i wouldn't call javascript "good" ol –  user151496 Commented Mar 5, 2018 at 0:18
  • 1 How does this admonition stand up in 2022? –  Ken Ingram Commented Mar 15, 2022 at 5:12
  • It is the responsibility of the end user to keep their browser updated. It is the responsibility of the developer to code in the right way and make the product better. –  user3221512 Commented Dec 7, 2022 at 11:10

Multiline string with variables

Abhishek Goel's user avatar

Not the answer you're looking for? Browse other questions tagged javascript string multiline heredoc or ask your own question .

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javascript assign multiple variables in one line

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COMMENTS

  1. Javascript How to define multiple variables on a single line?

    Reading documentation online, I'm getting confused how to properly define multiple JavaScript variables on a single line. If I want to condense the following code, what's the proper JavaScript "strict" way to define multiple javascript variables on a single line? var a = 0; var b = 0; Is it: var a = b = 0; or. var a = var b = 0; etc...

  2. javascript multiple variable assignment in one line

    as. var start = Date.now(); var diff; var minutes; var seconds; So you can declare multiple variables in one line as in code snippet 1 where we are initialising start but only declaring other variables. You can initialise multiple in one line like. var a = 1, b = 2, c = 3; answered Apr 23, 2018 at 15:24.

  3. Declare Multiple Variables in a Single Line in JavaScript

    let x, y, z; // Assign values to the variables later x = 5; y = 10; z = 15; However, you cannot use const keyword to declare multiple variables in one line and assign their values later. This is because each variable created with const keyword must be initialized with a value at the time of declaration. For example, this is not allowed:

  4. How to Declare Multiple Variables in a Single Line in JavaScript

    Declare Multiple Variables in a Single Line Using De-structuring Algorithm in JavaScript With the introduction of ES2015 (also known as ES6), the de-structuring algorithm was added to JavaScript, and it has quickly become one of the most valuable aspects of the language for two reasons:

  5. How to declare multiple Variables in JavaScript?

    Declaring Variables in a Single Line. You can declare multiple variables in a single line using the var, let, or const keyword followed by a comma-separated list of variable names. Syntax: let x = 20, y = 30, z = 40; Example: In this example, we are defining the three variables at once.

  6. How to Declare Multiple Variables at Once in JavaScript

    The most common way to declare multiple variables in JavaScript is to use commas to separate the variable names. This is the same as declaring each variable individually. let lastName; let age; You can also initialize them with values: You can improve readability by declaring each variable on a separate line:

  7. JavaScript declare multiple variables tutorial

    The declaration above just use one line, but it's a bit harder to read than separated declarations. Furthermore, all the variables are declared using the same keyword let. You can't use other variable keywords like const and var. You can also make a multi-line declaration using comma-separated declaration as shown below:

  8. Assign Multiple Variables to the Same Value in JavaScript

    We can also assign different values to different variables in the same line of code. For example: var a = 2, b = 3; After assigning the same value to multiple variables, if we update any of the variables, it will not affect others. In the example below, variables a, b, and c are assigned to 10 initially and then b is changed to 20.

  9. How to define multiple variables on a single line with JavaScript?

    Sometimes, we want to define multiple variables on a single line with JavaScript. In this article, we'll look at how to define multiple variables on a single line with JavaScript. To define multiple variables on a single line with JavaScript, we can use the array destructuring syntax.

  10. How to declare multiple variables in JavaScript

    This guide dives into the syntax and strategies for declaring multiple variables efficiently in JavaScript. ... You can group variable declarations without initialization and then assign values later: let firstName, lastName, age ... Like var, you can declare multiple variables in one line: let a = 'Hello', b = 'World', c = 100; Since let has ...

  11. Multiple Variable Assignment in JavaScript

    Output: 1, 1, 1, 1. undefined. The destructuring assignment helps in assigning multiple variables with the same value without leaking them outside the function. The fill() method updates all array elements with a static value and returns the modified array. You can read more about fill() here.

  12. Assign multiple variables to the same value in Javascript?

    The original variables you listed can be declared and assigned to the same value in a short line of code using destructuring assignment. The keywords let, const, and var can all be used for this type of assignment. let [moveUp, moveDown, moveLeft, moveRight, mouseDown, touchDown] = Array(6).fill(false); answered Jul 20, 2020 at 2:17.

  13. How to Declare Multiple Variables in JavaScript

    The code examples above demonstrate how to declare multiple variables in a single line of JavaScript. Still, declaring variables one by one is the most common method because it separates the declaration into its line, like the following example below. Example Code:

  14. Declare multiple variables in single line JavaScript

    Declare multiple variables in single line using destructuring assignment. let [name, age, country] = [ "StudyFame", 21, "United State" ]; document .write(name) document .write(age) document .write(country) Even you can declare a variable by using the let or var keyword one time and declaring multiple variables in a new inline.

  15. How to Declare Multiple Variables in One Line In JavaScript

    The comma operator in JavaScript allows you to combine multiple expressions into a single expression. When used in variable declarations, it enables you to declare multiple variables in a single line. Here's an example: let a = 1, b = 2, c = 3; In this example, we declare three variables a, b, and c in one line, assigning them values of 1, 2 ...

  16. Assigning Multiple Variables to the Same Value in JavaScript

    We assign the value 10 to all three variables in a single line of code. This is achieved by chaining the assignment operator (=) from one variable to the next. Benefits of Assigning Multiple Variables to the Same Value. Assigning multiple variables to the same value in JavaScript offers several benefits:

  17. JavaScript Variables

    All JavaScript variables must be identified with unique names. These unique names are called identifiers. Identifiers can be short names (like x and y) or more descriptive names (age, sum, totalVolume). The general rules for constructing names for variables (unique identifiers) are: Names can contain letters, digits, underscores, and dollar signs.

  18. How to set multiple variables at once in JavaScript?

    \$\begingroup\$ I'd argue that at least #1 and #3 do not matter in this case. The first code example does provide a "single place to look for" and minimizes globals just as much as the second example. In fact, the only example of those 4 that seems to make a difference in this case is #4 and, even then, not by much(in this particular case - assuming spaces are used - there are exactly as many ...

  19. Multiple variable assignment with Javascript

    Assigning multiple variables. Using the same set sort of examples as in the PHP post, but this time with Javascript, multiple variables can be assigned by using = multiple times on the same line of code like so: var c = b = a; The above is a more compact equivilent of this: var b = a; var c = b;

  20. User-defined variables in JavaScript

    To assign a JavaScript object to a variable, provide the name of the object, as in: myVar = window;; To assign a new copy of a user-defined object to a variable, use the new statement and provide ...

  21. javascript

    A simple way to print multiline strings in JavaScript is by using template literals (template strings) denoted by backticks (` `). you can also use variables inside a template string-like (` name is $ {value} `) You can also. const value = `multiline` const text = `This is a $ {value} string in js`; console.log (text);