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https://github.com/mathiasbynens/he

A robust HTML entity encoder/decoder written in JavaScript.
https://github.com/mathiasbynens/he

decode decoder encode encoder html-entities javascript

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A robust HTML entity encoder/decoder written in JavaScript.

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README 

        
# he [![Build status](https://travis-ci.org/mathiasbynens/he.svg?branch=master)](https://travis-ci.org/mathiasbynens/he) [![Code coverage status](https://codecov.io/github/mathiasbynens/he/coverage.svg?branch=master)](https://codecov.io/github/mathiasbynens/he?branch=master) [![Dependency status](https://gemnasium.com/mathiasbynens/he.svg)](https://gemnasium.com/mathiasbynens/he)



_he_ (for “HTML entities”) is a robust HTML entity encoder/decoder written in JavaScript. It supports [all standardized named character references as per HTML](https://html.spec.whatwg.org/multipage/syntax.html#named-character-references), handles [ambiguous ampersands](https://mathiasbynens.be/notes/ambiguous-ampersands) and other edge cases [just like a browser would](https://html.spec.whatwg.org/multipage/syntax.html#tokenizing-character-references), has an extensive test suite, and — contrary to many other JavaScript solutions — _he_ handles astral Unicode symbols just fine. [An online demo is available.](https://mothereff.in/html-entities)



## Installation



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



```bash

npm install he

```



Via [Bower](http://bower.io/):



```bash

bower install he

```



Via [Component](https://github.com/component/component):



```bash

component install mathiasbynens/he

```



In a browser:



```html



```



In [Node.js](https://nodejs.org/), [io.js](https://iojs.org/), [Narwhal](http://narwhaljs.org/), and [RingoJS](http://ringojs.org/):



```js

var he = require('he');

```



In [Rhino](http://www.mozilla.org/rhino/):



```js

load('he.js');

```



Using an AMD loader like [RequireJS](http://requirejs.org/):



```js

require(

  {

    'paths': {

      'he': 'path/to/he'

    }

  },

  ['he'],

  function(he) {

    console.log(he);

  }

);

```



## API



### `he.version`



A string representing the semantic version number.



### `he.encode(text, options)`



This function takes a string of text and encodes (by default) any symbols that aren’t printable ASCII symbols and `&`, `<`, `>`, `"`, `'`, and `` ` ``, replacing them with character references.



```js

he.encode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'

```



As long as the input string contains [allowed code points](https://html.spec.whatwg.org/multipage/parsing.html#preprocessing-the-input-stream) only, the return value of this function is always valid HTML. Any [(invalid) code points that cannot be represented using a character reference](https://html.spec.whatwg.org/multipage/syntax.html#table-charref-overrides) in the input are not encoded:



```js

he.encode('foo \0 bar');

// → 'foo \0 bar'

```



However, enabling [the `strict` option](https://github.com/mathiasbynens/he#strict) causes invalid code points to throw an exception. With `strict` enabled, `he.encode` either throws (if the input contains invalid code points) or returns a string of valid HTML.



The `options` object is optional. It recognizes the following properties:



#### `useNamedReferences`



The default value for the `useNamedReferences` option is `false`. This means that `encode()` will not use any named character references (e.g. `©`) in the output — hexadecimal escapes (e.g. `©`) will be used instead. Set it to `true` to enable the use of named references.



**Note that if compatibility with older browsers is a concern, this option should remain disabled.**



```js

// Using the global default setting (defaults to `false`):

he.encode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly disallow named references:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'useNamedReferences': false

});

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly allow named references:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'useNamedReferences': true

});

// → 'foo © bar ≠ baz 𝌆 qux'

```



#### `decimal`



The default value for the `decimal` option is `false`. If the option is enabled, `encode` will generally use decimal escapes (e.g. `©`) rather than hexadecimal escapes (e.g. `©`). Beside of this replacement, the basic behavior remains the same when combined with other options. For example: if both options `useNamedReferences` and `decimal` are enabled, named references (e.g. `©`) are used over decimal escapes. HTML entities without a named reference are encoded using decimal escapes.



```js

// Using the global default setting (defaults to `false`):

he.encode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly disable decimal escapes:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'decimal': false

});

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly enable decimal escapes:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'decimal': true

});

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly allow named references and decimal escapes:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'useNamedReferences': true,

  'decimal': true

});

// → 'foo © bar ≠ baz 𝌆 qux'

```



#### `encodeEverything`



The default value for the `encodeEverything` option is `false`. This means that `encode()` will not use any character references for printable ASCII symbols that don’t need escaping. Set it to `true` to encode every symbol in the input string. When set to `true`, this option takes precedence over `allowUnsafeSymbols` (i.e. setting the latter to `true` in such a case has no effect).



```js

// Using the global default setting (defaults to `false`):

he.encode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'



// Passing an `options` object to `encode`, to explicitly encode all symbols:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'encodeEverything': true

});

// → 'foo © bar ≠ baz 𝌆 qux'



// This setting can be combined with the `useNamedReferences` option:

he.encode('foo © bar ≠ baz 𝌆 qux', {

  'encodeEverything': true,

  'useNamedReferences': true

});

// → 'foo © bar ≠ baz 𝌆 qux'

```



#### `strict`



The default value for the `strict` option is `false`. This means that `encode()` will encode any HTML text content you feed it, even if it contains any symbols that cause [parse errors](https://html.spec.whatwg.org/multipage/parsing.html#preprocessing-the-input-stream). To throw an error when such invalid HTML is encountered, set the `strict` option to `true`. This option makes it possible to use _he_ as part of HTML parsers and HTML validators.



```js

// Using the global default setting (defaults to `false`, i.e. error-tolerant mode):

he.encode('\x01');

// → ''



// Passing an `options` object to `encode`, to explicitly enable error-tolerant mode:

he.encode('\x01', {

  'strict': false

});

// → ''



// Passing an `options` object to `encode`, to explicitly enable strict mode:

he.encode('\x01', {

  'strict': true

});

// → Parse error

```



#### `allowUnsafeSymbols`



The default value for the `allowUnsafeSymbols` option is `false`. This means that characters that are unsafe for use in HTML content (`&`, `<`, `>`, `"`, `'`, and `` ` ``) will be encoded. When set to `true`, only non-ASCII characters will be encoded. If the `encodeEverything` option is set to `true`, this option will be ignored.



```js

he.encode('foo © and & ampersand', {

  'allowUnsafeSymbols': true

});

// → 'foo © and & ampersand'

```



#### Overriding default `encode` options globally



The global default setting can be overridden by modifying the `he.encode.options` object. This saves you from passing in an `options` object for every call to `encode` if you want to use the non-default setting.



```js

// Read the global default setting:

he.encode.options.useNamedReferences;

// → `false` by default



// Override the global default setting:

he.encode.options.useNamedReferences = true;



// Using the global default setting, which is now `true`:

he.encode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'

```



### `he.decode(html, options)`



This function takes a string of HTML and decodes any named and numerical character references in it using [the algorithm described in section 12.2.4.69 of the HTML spec](https://html.spec.whatwg.org/multipage/syntax.html#tokenizing-character-references).



```js

he.decode('foo © bar ≠ baz 𝌆 qux');

// → 'foo © bar ≠ baz 𝌆 qux'

```



The `options` object is optional. It recognizes the following properties:



#### `isAttributeValue`



The default value for the `isAttributeValue` option is `false`. This means that `decode()` will decode the string as if it were used in [a text context in an HTML document](https://html.spec.whatwg.org/multipage/syntax.html#data-state). HTML has different rules for [parsing character references in attribute values](https://html.spec.whatwg.org/multipage/syntax.html#character-reference-in-attribute-value-state) — set this option to `true` to treat the input string as if it were used as an attribute value.



```js

// Using the global default setting (defaults to `false`, i.e. HTML text context):

he.decode('foo&ampbar');

// → 'foo&bar'



// Passing an `options` object to `decode`, to explicitly assume an HTML text context:

he.decode('foo&ampbar', {

  'isAttributeValue': false

});

// → 'foo&bar'



// Passing an `options` object to `decode`, to explicitly assume an HTML attribute value context:

he.decode('foo&ampbar', {

  'isAttributeValue': true

});

// → 'foo&ampbar'

```



#### `strict`



The default value for the `strict` option is `false`. This means that `decode()` will decode any HTML text content you feed it, even if it contains any entities that cause [parse errors](https://html.spec.whatwg.org/multipage/syntax.html#tokenizing-character-references). To throw an error when such invalid HTML is encountered, set the `strict` option to `true`. This option makes it possible to use _he_ as part of HTML parsers and HTML validators.



```js

// Using the global default setting (defaults to `false`, i.e. error-tolerant mode):

he.decode('foo&ampbar');

// → 'foo&bar'



// Passing an `options` object to `decode`, to explicitly enable error-tolerant mode:

he.decode('foo&ampbar', {

  'strict': false

});

// → 'foo&bar'



// Passing an `options` object to `decode`, to explicitly enable strict mode:

he.decode('foo&ampbar', {

  'strict': true

});

// → Parse error

```



#### Overriding default `decode` options globally



The global default settings for the `decode` function can be overridden by modifying the `he.decode.options` object. This saves you from passing in an `options` object for every call to `decode` if you want to use a non-default setting.



```js

// Read the global default setting:

he.decode.options.isAttributeValue;

// → `false` by default



// Override the global default setting:

he.decode.options.isAttributeValue = true;



// Using the global default setting, which is now `true`:

he.decode('foo&ampbar');

// → 'foo&ampbar'

```



### `he.escape(text)`



This function takes a string of text and escapes it for use in text contexts in XML or HTML documents. Only the following characters are escaped: `&`, `<`, `>`, `"`, `'`, and `` ` ``.



```js

he.escape('');

// → '<img src='x' onerror="prompt(1)">'

```



### `he.unescape(html, options)`



`he.unescape` is an alias for `he.decode`. It takes a string of HTML and decodes any named and numerical character references in it.



### Using the `he` binary



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



```bash

npm install -g he

```



After that you will be able to encode/decode HTML entities from the command line:



```bash

$ he --encode 'föo ♥ bår 𝌆 baz'

föo ♥ bår 𝌆 baz



$ he --encode --use-named-refs 'föo ♥ bår 𝌆 baz'

föo ♥ bår 𝌆 baz



$ he --decode 'föo ♥ bår 𝌆 baz'

föo ♥ bår 𝌆 baz

```



Read a local text file, encode it for use in an HTML text context, and save the result to a new file:



```bash

$ he --encode < foo.txt > foo-escaped.html

```



Or do the same with an online text file:



```bash

$ curl -sL "http://git.io/HnfEaw" | he --encode > escaped.html

```



Or, the opposite — read a local file containing a snippet of HTML in a text context, decode it back to plain text, and save the result to a new file:



```bash

$ he --decode < foo-escaped.html > foo.txt

```



Or do the same with an online HTML snippet:



```bash

$ curl -sL "http://git.io/HnfEaw" | he --decode > decoded.txt

```



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



## Support



_he_ has been tested in at least:



* Chrome 27-50

* Firefox 3-45

* Safari 4-9

* Opera 10-12, 15–37

* IE 6–11

* Edge

* Narwhal 0.3.2

* Node.js v0.10, v0.12, v4, v5

* PhantomJS 1.9.0

* Rhino 1.7RC4

* RingoJS 0.8-0.11



## Unit tests & code coverage



After cloning this repository, run `npm install` to install the dependencies needed for he 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`.



## Acknowledgements



Thanks to [Simon Pieters](https://simon.html5.org/) ([@zcorpan](https://twitter.com/zcorpan)) for the many suggestions.



## Author



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

|---|

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



## License



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