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, handles ambiguous ampersands and other edge cases just like a browser would, has an extensive test suite, and — contrary to many other JavaScript solutions — he handles astral Unicode symbols just fine. An online demo is available.
Installation
Via npm:
npm install he
Via Bower:
bower install he
Via Component:
component install mathiasbynens/he
In a browser:
<script src="he.js"></script>
In Node.js, io.js, Narwhal, and RingoJS:
var he = require('he');
In Rhino:
load('he.js');
Using an AMD loader like RequireJS:
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.
.encode('foo © bar ≠ baz 𝌆 qux');
he// → 'foo © bar ≠ baz 𝌆 qux'
As long as the input string contains allowed code points only, the return value of this function is always valid HTML. Any (invalid) code points that cannot be represented using a character reference in the input are not encoded:
.encode('foo \0 bar');
he// → 'foo \0 bar'
However, enabling the
strict
option 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.
// Using the global default setting (defaults to `false`):
.encode('foo © bar ≠ baz 𝌆 qux');
he// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly disallow named references:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'useNamedReferences': false
;
})// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly allow named references:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'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.
// Using the global default setting (defaults to `false`):
.encode('foo © bar ≠ baz 𝌆 qux');
he// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly disable decimal escapes:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'decimal': false
;
})// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly enable decimal escapes:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'decimal': true
;
})// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly allow named references and decimal escapes:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'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).
// Using the global default setting (defaults to `false`):
.encode('foo © bar ≠ baz 𝌆 qux');
he// → 'foo © bar ≠ baz 𝌆 qux'
// Passing an `options` object to `encode`, to explicitly encode all symbols:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'encodeEverything': true
;
})// → 'foo © bar ≠ baz 𝌆 qux'
// This setting can be combined with the `useNamedReferences` option:
.encode('foo © bar ≠ baz 𝌆 qux', {
he'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. 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.
// Using the global default setting (defaults to `false`, i.e. error-tolerant mode):
.encode('\x01');
he// → ''
// Passing an `options` object to `encode`, to explicitly enable error-tolerant mode:
.encode('\x01', {
he'strict': false
;
})// → ''
// Passing an `options` object to `encode`, to explicitly enable strict mode:
.encode('\x01', {
he'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.
.encode('foo © and & ampersand', {
he'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.
// Read the global default setting:
.encode.options.useNamedReferences;
he// → `false` by default
// Override the global default setting:
.encode.options.useNamedReferences = true;
he
// Using the global default setting, which is now `true`:
.encode('foo © bar ≠ baz 𝌆 qux');
he// → '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.
.decode('foo © bar ≠ baz 𝌆 qux');
he// → '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. HTML has different rules for parsing
character references in attribute values — set this option to
true
to treat the input string as if it were used as an
attribute value.
// Using the global default setting (defaults to `false`, i.e. HTML text context):
.decode('foo&bar');
he// → 'foo&bar'
// Passing an `options` object to `decode`, to explicitly assume an HTML text context:
.decode('foo&bar', {
he'isAttributeValue': false
;
})// → 'foo&bar'
// Passing an `options` object to `decode`, to explicitly assume an HTML attribute value context:
.decode('foo&bar', {
he'isAttributeValue': true
;
})// → 'foo&bar'
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. 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.
// Using the global default setting (defaults to `false`, i.e. error-tolerant mode):
.decode('foo&bar');
he// → 'foo&bar'
// Passing an `options` object to `decode`, to explicitly enable error-tolerant mode:
.decode('foo&bar', {
he'strict': false
;
})// → 'foo&bar'
// Passing an `options` object to `decode`, to explicitly enable strict mode:
.decode('foo&bar', {
he'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.
// Read the global default setting:
.decode.options.isAttributeValue;
he// → `false` by default
// Override the global default setting:
.decode.options.isAttributeValue = true;
he
// Using the global default setting, which is now `true`:
.decode('foo&bar');
he// → 'foo&bar'
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 `
.
.escape('<img src=\'x\' onerror="prompt(1)">');
he// → '<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:
npm install -g he
After that you will be able to encode/decode HTML entities from the command line:
$ 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:
$ he --encode < foo.txt > foo-escaped.html
Or do the same with an online text file:
$ 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:
$ he --decode < foo-escaped.html > foo.txt
Or do the same with an online HTML snippet:
$ 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 (@zcorpan) for the many suggestions.
Author
Mathias Bynens |
License
he is available under the MIT license.