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https://github.com/mathiasbynens/jsesc

Given some data, jsesc returns the shortest possible stringified & ASCII-safe representation of that data.
https://github.com/mathiasbynens/jsesc

ascii-safe code-generation ecmascript escape escape-sequences javascript json stringify unicode

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Given some data, jsesc returns the shortest possible stringified & ASCII-safe representation of that data.

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# jsesc



Given some data, _jsesc_ returns a stringified representation of that data. jsesc is similar to `JSON.stringify()` except:



1. it outputs JavaScript instead of JSON [by default](#json), enabling support for data structures like ES6 maps and sets;

2. it offers [many options](#api) to customize the output;

3. its output is ASCII-safe [by default](#minimal), thanks to its use of [escape sequences](https://mathiasbynens.be/notes/javascript-escapes) where needed.



For any input, jsesc generates the shortest possible valid printable-ASCII-only output. [Here’s an online demo.](https://mothereff.in/js-escapes)



jsesc’s output can be used instead of `JSON.stringify`’s to avoid [mojibake](https://en.wikipedia.org/wiki/Mojibake) and other encoding issues, or even to [avoid errors](https://twitter.com/annevk/status/380000829643571200) when passing JSON-formatted data (which may contain U+2028 LINE SEPARATOR, U+2029 PARAGRAPH SEPARATOR, or [lone surrogates](https://esdiscuss.org/topic/code-points-vs-unicode-scalar-values#content-14)) to a JavaScript parser or an UTF-8 encoder.



## Installation



Via [npm](https://www.npmjs.com/):



```bash

npm install jsesc

```



In [Node.js](https://nodejs.org/):



```js

const jsesc = require('jsesc');

```



## API



### `jsesc(value, options)`



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](https://mathiasbynens.be/notes/javascript-escapes). The first supported value type is strings:



```js

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, an object, a map, a set, a number, a BigInt, or a buffer. In such cases, `jsesc` returns a stringified version of the value where any characters that are not printable ASCII symbols are escaped in the same way.



```js

// 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:



#### `quotes`



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



```js

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'`.



```js

jsesc('`Lorem` ipsum "dolor" sit \'amet\' etc.', {

  'quotes': 'double'

});

// → '`Lorem` ipsum \\"dolor\\" sit \'amet\' etc.'

// → "`Lorem` ipsum \\\"dolor\\\" sit 'amet' etc."

```



If you want to use the output as part of a template literal (i.e. wrapped in backticks), set the `quotes` option to `'backtick'`.



```js

jsesc('`Lorem` ipsum "dolor" sit \'amet\' etc.', {

  'quotes': 'backtick'

});

// → '\\`Lorem\\` ipsum "dolor" sit \'amet\' etc.'

// → "\\`Lorem\\` ipsum \"dolor\" sit 'amet' etc."

// → `\\\`Lorem\\\` ipsum "dolor" sit 'amet' etc.`

```



This setting also affects the output for arrays and objects:



```js

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"]'

```



#### `numbers`



The default value for the `numbers` option is `'decimal'`. This means that any numeric values are represented using decimal integer literals. Other valid options are `binary`, `octal`, and `hexadecimal`, which result in binary integer literals, octal integer literals, and hexadecimal integer literals, respectively.



```js

jsesc(42, {

  'numbers': 'binary'

});

// → '0b101010'



jsesc(42, {

  'numbers': 'octal'

});

// → '0o52'



jsesc(42, {

  'numbers': 'decimal'

});

// → '42'



jsesc(42, {

  'numbers': 'hexadecimal'

});

// → '0x2A'

```



#### `wrap`



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



```js

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.\""

```



#### `es6`



The `es6` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, any astral Unicode symbols in the input are escaped using [ECMAScript 6 Unicode code point escape sequences](https://mathiasbynens.be/notes/javascript-escapes#unicode-code-point) 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`).



```js

// 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'

```



#### `escapeEverything`



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



```js

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 string literals within arrays and objects.



#### `minimal`



The `minimal` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, only a limited set of symbols in the output are escaped:



* U+0000 `\0`

* U+0008 `\b`

* U+0009 `\t`

* U+000A `\n`

* U+000C `\f`

* U+000D `\r`

* U+005C `\\`

* U+2028 `\u2028`

* U+2029 `\u2029`

* whatever symbol is being used for wrapping string literals (based on [the `quotes` option](#quotes))

* [lone surrogates](https://esdiscuss.org/topic/code-points-vs-unicode-scalar-values#content-14)



Note: with this option enabled, jsesc output is no longer guaranteed to be ASCII-safe.



```js

jsesc('foo\u2029bar\nbaz©qux𝌆flops', {

  'minimal': false

});

// → 'foo\\u2029bar\\nbaz©qux𝌆flops'

```



#### `isScriptContext`



The `isScriptContext` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, occurrences of [`` or `` element in an HTML document.



```js

jsesc('foo</script>bar', {

  'isScriptContext': true

});

// → 'foo<\\/script>bar'

```



#### `compact`



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



```js

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.



#### `indent`



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



```js

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.



#### `indentLevel`



The `indentLevel` option takes a numeric value, and defaults to `0`. It represents the current indentation level, i.e. the number of times the value of [the `indent` option](#indent) is repeated.



```js

jsesc(['a', 'b', 'c'], {

  'compact': false,

  'indentLevel': 1

});

// → '[\n\t\t\'a\',\n\t\t\'b\',\n\t\t\'c\'\n\t]'



jsesc(['a', 'b', 'c'], {

  'compact': false,

  'indentLevel': 2

});

// → '[\n\t\t\t\'a\',\n\t\t\t\'b\',\n\t\t\t\'c\'\n\t\t]'

```



#### `json`



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](https://mathiasbynens.be/notes/javascript-escapes#hexadecimal) and [the `\v` or `\0` escape sequences](https://mathiasbynens.be/notes/javascript-escapes#single) are not 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.



```js

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](http://bestiejs.github.io/json3/).



#### `lowercaseHex`



The `lowercaseHex` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, any alphabetical hexadecimal digits in escape sequences as well as any hexadecimal integer literals (see [the `numbers` option](#numbers)) in the output are in lowercase.



```js

jsesc('Ich ♥ Bücher', {

  'lowercaseHex': true

});

// → 'Ich \\u2665 B\\xfccher'

//                    ^^



jsesc(42, {

  'numbers': 'hexadecimal',

  'lowercaseHex': true

});

// → '0x2a'

//      ^^

```



### `jsesc.version`



A string representing the semantic version number.



### Using the `jsesc` binary



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



```bash

npm install -g jsesc

```



After that you’re able to escape strings from the command line:



```bash

$ 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:



```bash

$ 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:



```bash

$ jsesc --pretty '{ "föo": "♥", "bår": "𝌆 baz" }'

{

  'f\xF6o': '\u2665',

  'b\xE5r': '\uD834\uDF06 baz'

}

```



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



```bash

$ 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:



```bash

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

```



Or do the same with an online JSON file:



```bash

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

```



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



## Support



As of v3.0.0, jsesc supports Node.js v6+ only.



Older versions (up to jsesc v1.3.0) support Chrome 27, Firefox 3, Safari 4, Opera 10, IE 6, Node.js v6.0.0, Narwhal 0.3.2, RingoJS 0.8-0.11, 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](https://bestiejs.github.io/json3/).



## Author



| [![twitter/mathias](https://gravatar.com/avatar/24e08a9ea84deb17ae121074d0f17125?s=70)](https://twitter.com/mathias "Follow @mathias on Twitter") |

|---|

| [Mathias Bynens](https://mathiasbynens.be/) |



## License



This library is available under the [MIT](https://mths.be/mit) license.