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, enabling support for data structures like ES6 maps and sets;
2. it offers many options to customize the output;
3. its output is ASCII-safe by default, thanks to its use of escape sequences where needed.

For any input, jsesc generates the shortest possible valid printable-ASCII-only output. Here’s an online demo.

jsesc’s output can be used instead of `JSON.stringify`’s 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.

# Installation

Via npm:

npm install jsesc

In Node.js:

const jsesc = require('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, an object, a map, a set, 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.

// 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 occurrences of`'`in the input string are 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."

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

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:

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>numbers</tt>

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.

jsesc(42, {
'numbers': 'binary'
});
// → '0b101010'
jsesc(42, {
'numbers': 'octal'
});
// → '0o52'
jsesc(42, {
'numbers': 'decimal'
});
// → '42'
jsesc(42, {
'numbers': 'hexadecimal'
});
// → '0x2A'

### <tt>wrap</tt>

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.

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 are 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 are 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 string literals within arrays and objects.

### <tt>minimal</tt>

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)

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

jsesc('foo\u2029bar\nbaz©qux𝌆flops', {
'minimal': false
});
// → 'foo\\u2029bar\\nbaz©qux𝌆flops'

### <tt>isScriptContext</tt>

The `isScriptContext` option takes a boolean value (`true` or `false`), and defaults to `false` (disabled). When enabled, occurrences of `</script` and `</style` in the output are escaped as `<\/script` and `<\/style`, and `<!--` is escaped as `\x3C!--` (or `\u003C!--` when the `json` option is enabled). This setting is useful when jsesc’s output ends up as part of a `<script>` or `<style>` element in an HTML document.

jsesc('foo</script>bar', {
'isScriptContext': true
});
// → 'foo<\\/script>bar'

### <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 is as compact as possible; it’s not 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>indentLevel</tt>

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 is repeated.

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]'

### <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 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.

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>lowercaseHex</tt>

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) in the output are in lowercase.

jsesc('Ich ♥ Bücher', {
'lowercaseHex': true
});
// → 'Ich \\u2665 B\\xfccher'
// ^^
jsesc(42, {
'numbers': 'hexadecimal',
'lowercaseHex': true
});
// → '0x2a'
// ^^

## <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’re 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

As of v2.0.0, jsesc supports Node.js v4+ 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.

# Author

Mathias Bynens

# License

This library is available under the MIT license.