jsesc

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

it outputs JavaScript instead of JSON by default, enabling support for data structures like ES6 maps and sets;
it offers many options to customize the output;
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

`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. 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, 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.

// 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.

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"]'

`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.

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.

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 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'

`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.

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)
lone surrogates

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'

`isScriptContext`

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'

`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.

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.

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 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]'

`json`

The json option takes a boolean value (true or false), and defaults to false (disabled). When enabled, the output is valid JSON. [Hexadecimal char

Jsesc

Install / Use

README