Creating multiline strings in JavaScript

Question

I have the following code in Ruby. I want to convert this code into JavaScript. what's the equivalent code in JS?

text = <<"HERE"
This
Is
A
Multiline
String
HERE

Answer 1

Update:

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:

var html = `
  <div>
    <span>Some HTML here</span>
  </div>
`;

(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:

"foo \
bar"

Answer 2

You can use += to concatenate your string, seems like no one answered that, which will be readable, and also neat... something like this

var hello = 'hello' +
            'world' +
            'blah';

can be also written as

var hello = 'hello';
    hello += ' world';
    hello += ' blah';

console.log(hello);

Answer 3

There are multiple ways to achieve this

1. Slash concatenation

  var MultiLine=  '1\
    2\
    3\
    4\
    5\
    6\
    7\
    8\
    9';

2. regular concatenation

var MultiLine = '1'
+'2'
+'3'
+'4'
+'5';

3. Array Join concatenation

var MultiLine = [
'1',
'2',
'3',
'4',
'5'
].join('');

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

Refer this test case for more details regarding the performance

Update:

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

Example:

 `<h1>{{title}}</h1>
  <h2>{{hero.name}} details!</h2>
  <div><label>id: </label>{{hero.id}}</div>
  <div><label>name: </label>{{hero.name}}</div>
  `

Answer 4

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

var template = require('text!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.

var fs = require("fs");
var template = fs.readFileSync(template.html', 'utf8');

Easy.

Answer 5

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.

var myString = function(){/*
    This is some
    awesome multi-lined
    string using a comment 
    inside a function 
    returned as a string.
    Enjoy the jimmy rigged code.
*/}.toString().slice(14,-3)

alert(myString)

Answer 6

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

var templates = {
    myString: `this is
a multiline
string` 
}

alert(templates.myString);

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

var templates = 
{
 myString: function(){/*
    This is some
    awesome multi-lined
    string using a comment 
    inside a function 
    returned as a string.
    Enjoy the jimmy rigged code.
*/}.toString().slice(14,-3)

}
alert(templates.myString)

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):

interface externTemplates
{
    myString:string;
}

declare var templates:externTemplates;

alert(templates.myString)

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