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jsesc

This is a JavaScript library for escaping JavaScript strings while generating the shortest possible valid ASCII-only output. Here’s an online demo.

This can be used to avoid mojibake and other encoding issues, or even to avoid errors when passing JSON-formatted data (which may contain U+2028 LINE SEPARATOR, U+2029 PARAGRAPH SEPARATOR, or lone surrogates) to a JavaScript parser or an UTF-8 encoder, respectively.

Feel free to fork if you see possible improvements!

# Installation

Via Bower:

bower install jsesc

Via Component:

component install mathiasbynens/jsesc

Via npm:

npm install jsesc

In a browser:

<script src="jsesc.js"></script>

In Node.js and RingoJS:

var jsesc = require('jsesc');

In Narwhal:

var jsesc = require('jsesc').jsesc;

In Rhino:

load('jsesc.js');

Using an AMD loader like RequireJS:

require(
{
'paths': {
'jsesc': 'path/to/jsesc'
}
},
['jsesc'],
function(jsesc) {
console.log(jsesc);
}
);

# API

## <tt>jsesc(value, options)</tt>

This function takes a value and returns an escaped version of the value where any characters that are not printable ASCII symbols are escaped using the shortest possible (but valid) escape sequences for use in JavaScript strings. The first supported value type is strings:

jsesc('Ich ♥ Bücher');
// → 'Ich \\u2665 B\\xFCcher'
jsesc('foo 𝌆 bar');
// → 'foo \\uD834\\uDF06 bar'

Instead of a string, the `value` can also be an array, or an object. In such cases, `jsesc` will return a stringified version of the value where any characters that are not printable ASCII symbols are escaped in the same way.

// Escaping an array
jsesc([
'Ich ♥ Bücher', 'foo 𝌆 bar'
]);
// → '[\'Ich \\u2665 B\\xFCcher\',\'foo \\uD834\\uDF06 bar\']'
// Escaping an object
jsesc({
'Ich ♥ Bücher': 'foo 𝌆 bar'
});
// → '{\'Ich \\u2665 B\\xFCcher\':\'foo \\uD834\\uDF06 bar\'}'

The optional `options` argument accepts an object with the following options:

### <tt>quotes</tt>

The default value for the `quotes` option is ‘'single’`. This means that any occurences of`'`in the input string will be escaped as`\'`, so that the output can be used in a string literal wrapped in single quotes.

jsesc('Lorem ipsum "dolor" sit \'amet\' etc.');
// → 'Lorem ipsum "dolor" sit \\\'amet\\\' etc.'
jsesc('Lorem ipsum "dolor" sit \'amet\' etc.', {
'quotes': 'single'
});
// → 'Lorem ipsum "dolor" sit \\\'amet\\\' etc.'
// → "Lorem ipsum \"dolor\" sit \\'amet\\' etc."

If you want to use the output as part of a string literal wrapped in double quotes, set the `quotes` option to ‘'double’`.

jsesc('Lorem ipsum "dolor" sit \'amet\' etc.', {
'quotes': 'double'
});
// → 'Lorem ipsum \\"dolor\\" sit \'amet\' etc.'
// → "Lorem ipsum \\\"dolor\\\" sit 'amet' etc."

This setting also affects the output for arrays and objects:

jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'quotes': 'double'
});
// → '{"Ich \\u2665 B\\xFCcher":"foo \\uD834\\uDF06 bar"}'
jsesc([ 'Ich ♥ Bücher', 'foo 𝌆 bar' ], {
'quotes': 'double'
});
// → '["Ich \\u2665 B\\xFCcher","foo \\uD834\\uDF06 bar"]'

### <tt>wrap</tt>

The `wrap` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, the output will be a valid JavaScript string literal wrapped in quotes. The type of quotes can be specified through the `quotes` setting.

jsesc('Lorem ipsum "dolor" sit \'amet\' etc.', {
'quotes': 'single',
'wrap': true
});
// → '\'Lorem ipsum "dolor" sit \\\'amet\\\' etc.\''
// → "\'Lorem ipsum \"dolor\" sit \\\'amet\\\' etc.\'"
jsesc('Lorem ipsum "dolor" sit \'amet\' etc.', {
'quotes': 'double',
'wrap': true
});
// → '"Lorem ipsum \\"dolor\\" sit \'amet\' etc."'
// → "\"Lorem ipsum \\\"dolor\\\" sit \'amet\' etc.\""

### <tt>es6</tt>

The `es6` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, any astral Unicode symbols in the input will be escaped using ECMAScript 6 Unicode code point escape sequences instead of using separate escape sequences for each surrogate half. If backwards compatibility with ES5 environments is a concern, don’t enable this setting. If the `json` setting is enabled, the value for the `es6` setting is ignored (as if it was `false`).

// By default, the `es6` option is disabled:
jsesc('foo 𝌆 bar 💩 baz');
// → 'foo \\uD834\\uDF06 bar \\uD83D\\uDCA9 baz'
// To explicitly disable it:
jsesc('foo 𝌆 bar 💩 baz', {
'es6': false
});
// → 'foo \\uD834\\uDF06 bar \\uD83D\\uDCA9 baz'
// To enable it:
jsesc('foo 𝌆 bar 💩 baz', {
'es6': true
});
// → 'foo \\u{1D306} bar \\u{1F4A9} baz'

### <tt>escapeEverything</tt>

The `escapeEverything` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, all the symbols in the output will be escaped, even printable ASCII symbols.

jsesc('lolwat"foo\'bar', {
'escapeEverything': true
});
// → '\\x6C\\x6F\\x6C\\x77\\x61\\x74\\"\\x66\\x6F\\x6F\\\'\\x62\\x61\\x72'
// → "\\x6C\\x6F\\x6C\\x77\\x61\\x74\\\"\\x66\\x6F\\x6F\\'\\x62\\x61\\x72"

This setting also affects the output for arrays and objects:

jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'escapeEverything': true
});
// → '{\'\x49\x63\x68\x20\u2665\x20\x42\xFC\x63\x68\x65\x72\':\'\x66\x6F\x6F\x20\uD834\uDF06\x20\x62\x61\x72\'}'
// → "{'\x49\x63\x68\x20\u2665\x20\x42\xFC\x63\x68\x65\x72':'\x66\x6F\x6F\x20\uD834\uDF06\x20\x62\x61\x72'}"
jsesc([ 'Ich ♥ Bücher': 'foo 𝌆 bar' ], {
'escapeEverything': true
});
// → '[\'\x49\x63\x68\x20\u2665\x20\x42\xFC\x63\x68\x65\x72\',\'\x66\x6F\x6F\x20\uD834\uDF06\x20\x62\x61\x72\']'

### <tt>compact</tt>

The `compact` option takes a boolean value (`true` or `false`), and defaults to `true` (enabled). When enabled, the output for arrays and objects will be as compact as possible; it won’t be formatted nicely.

jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'compact': true // this is the default
});
// → '{\'Ich \u2665 B\xFCcher\':\'foo \uD834\uDF06 bar\'}'
jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'compact': false
});
// → '{\n\t\'Ich \u2665 B\xFCcher\': \'foo \uD834\uDF06 bar\'\n}'
jsesc([ 'Ich ♥ Bücher', 'foo 𝌆 bar' ], {
'compact': false
});
// → '[\n\t\'Ich \u2665 B\xFCcher\',\n\t\'foo \uD834\uDF06 bar\'\n]'

This setting has no effect on the output for strings.

### <tt>indent</tt>

The `indent` option takes a string value, and defaults to ‘’\t'`. When the`compact`setting is enabled (`true`), the value of the`indent` option is used to format the output for arrays and objects.

jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'compact': false,
'indent': '\t' // this is the default
});
// → '{\n\t\'Ich \u2665 B\xFCcher\': \'foo \uD834\uDF06 bar\'\n}'
jsesc({ 'Ich ♥ Bücher': 'foo 𝌆 bar' }, {
'compact': false,
'indent': ' '
});
// → '{\n \'Ich \u2665 B\xFCcher\': \'foo \uD834\uDF06 bar\'\n}'
jsesc([ 'Ich ♥ Bücher', 'foo 𝌆 bar' ], {
'compact': false,
'indent': ' '
});
// → '[\n \'Ich \u2665 B\xFCcher\',\n\ t\'foo \uD834\uDF06 bar\'\n]'

This setting has no effect on the output for strings.

### <tt>json</tt>

The `json` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, the output is valid JSON. Hexadecimal character escape sequences and the `\v` or `\0` escape sequences will not be used. Setting `json: true` implies ‘quotes: 'double’, wrap: true, es6: false`, although these values can still be overridden if needed — but in such cases, the output won’t be valid JSON anymore.

jsesc('foo\x00bar\xFF\uFFFDbaz', {
'json': true
});
// → '"foo\\u0000bar\\u00FF\\uFFFDbaz"'
jsesc({ 'foo\x00bar\xFF\uFFFDbaz': 'foo\x00bar\xFF\uFFFDbaz' }, {
'json': true
});
// → '{"foo\\u0000bar\\u00FF\\uFFFDbaz":"foo\\u0000bar\\u00FF\\uFFFDbaz"}'
jsesc([ 'foo\x00bar\xFF\uFFFDbaz', 'foo\x00bar\xFF\uFFFDbaz' ], {
'json': true
});
// → '["foo\\u0000bar\\u00FF\\uFFFDbaz","foo\\u0000bar\\u00FF\\uFFFDbaz"]'
// Values that are acceptable in JSON but aren’t strings, arrays, or object
// literals can’t be escaped, so they’ll just be preserved:
jsesc([ 'foo\x00bar', [1, '©', { 'foo': true, 'qux': null }], 42 ], {
'json': true
});
// → '["foo\\u0000bar",[1,"\\u00A9",{"foo":true,"qux":null}],42]'
// Values that aren’t allowed in JSON are run through `JSON.stringify()`:
jsesc([ undefined, -Infinity ], {
'json': true
});
// → '[null,null]'

Note: Using this option on objects or arrays that contain non-string values relies on `JSON.stringify()`. For legacy environments like IE ≤ 7, use a `JSON` polyfill.

## <tt>jsesc.version</tt>

A string representing the semantic version number.

## Using the <tt>jsesc</tt> binary

To use the `jsesc` binary in your shell, simply install jsesc globally using npm:

npm install -g jsesc

After that you will be able to escape strings from the command line:

$ jsesc 'föo ♥ bår 𝌆 baz'
f\xF6o \u2665 b\xE5r \uD834\uDF06 baz

To escape arrays or objects containing string values, use the `-o`/`--object` option:

$ jsesc --object '{ "föo": "♥", "bår": "𝌆 baz" }'
{'f\xF6o':'\u2665','b\xE5r':'\uD834\uDF06 baz'}

To prettify the output in such cases, use the `-p`/`--pretty` option:

$ jsesc --pretty '{ "föo": "♥", "bår": "𝌆 baz" }'
{
'f\xF6o': '\u2665',
'b\xE5r': '\uD834\uDF06 baz'
}

For valid JSON output, use the `-j`/`--json` option:

$ jsesc --json --pretty '{ "föo": "♥", "bår": "𝌆 baz" }'
{
"f\u00F6o": "\u2665",
"b\u00E5r": "\uD834\uDF06 baz"
}

Read a local JSON file, escape any non-ASCII symbols, and save the result to a new file:

$ jsesc --json --object < data-raw.json > data-escaped.json

Or do the same with an online JSON file:

$ curl -sL "http://git.io/aorKgQ" | jsesc --json --object > data-escaped.json

See `jsesc --help` for the full list of options.

# Support

This library has been tested in at least Chrome 27-29, Firefox 3-22, Safari 4-6, Opera 10-12, IE 6-10, Node.js v0.10.0, Narwhal 0.3.2, RingoJS 0.8-0.9, PhantomJS 1.9.0, and Rhino 1.7RC4.

Note: Using the `json` option on objects or arrays that contain non-string values relies on `JSON.parse()`. For legacy environments like IE ≤ 7, use a `JSON` polyfill.

# Unit tests & code coverage

After cloning this repository, run `npm install` to install the dependencies needed for development and testing. You may want to install Istanbul globally using `npm install istanbul -g`.

Once that’s done, you can run the unit tests in Node using `npm test` or `node tests/tests.js`. To run the tests in Rhino, Ringo, Narwhal, and web browsers as well, use `grunt test`.

To generate the code coverage report, use `grunt cover`.

# Author

Mathias Bynens

# License

This library is available under the MIT license.