README.md



JS-YAML - YAML 1.2 parser and serializer for JavaScript


Online Demo

This is an implementation of YAML, a human friendly data
serialization language. Started as PyYAML port, it was
completely rewritten from scratch. Now it's very fast, and supports 1.2 spec.


Breaking changes in 1.x.x -> 2.0.x

If your have not used custom tags or loader classes - no changes needed. Just
upgrade library and enjoy high parse speed.

In other case, you should rewrite your tag constructors and custom loader
classes, to conform new schema-based API. See
examples and
wiki for details.
Note, that parser internals were completely rewritten.


Installation


YAML module for node.js

npm install js-yaml


CLI executable

If you want to inspect your YAML files from CLI, install js-yaml globally:

npm install js-yaml -g


Usage

usage: js-yaml [-h] [-v] [-c] [-j] [-t] file

Positional arguments:
  file           File with YAML document(s)

Optional arguments:
  -h, --help     Show this help message and exit.
  -v, --version  Show program's version number and exit.
  -c, --compact  Display errors in compact mode
  -j, --to-json  Output a non-funky boring JSON
  -t, --trace    Show stack trace on error


Bundled YAML library for browsers

<script src="js-yaml.min.js"></script>
<script type="text/javascript">
var doc = jsyaml.load('greeting: hello\nname: world');
</script>


Browser support was done mostly for online demo. If you find any errors - feel
free to send pull requests with fixes. Also note, that IE and other old browsers
needs es5-shims to operate.


API

Here we cover the most 'useful' methods. If you need advanced details (creating
your own tags), see wiki and
examples for more
info.

In node.js JS-YAML automatically registers handlers for .yml and .yaml
files. You can load them just with require. That's mostly equivalent to
calling load() on fetched content of a file. Just with one string!

require('js-yaml');

// Get document, or throw exception on error
try {
  var doc = require('/home/ixti/example.yml');
  console.log(doc);
} catch (e) {
  console.log(e);
}


load (string [ , options ])

Parses string as single YAML document. Returns a JavaScript object or throws
YAMLException on error.

NOTE: This function does not understands multi-document sources, it throws
exception on those.

options:


filename (default: null) - string to be used as a file path in
error/warning messages.

strict (default - false) makes the loader to throw errors instead of
warnings.

schema (default: DEFAULT_SCHEMA) - specifies a schema to use.


loadAll (string, iterator [ , options ])

Same as load(), but understands multi-document sources and apply iterator to
each document.

var yaml = require('js-yaml');

yaml.loadAll(data, function (doc) {
  console.log(doc);
});


safeLoad (string [ , options ])

Same as load() but uses SAFE_SCHEMA by default - only recommended tags of
YAML specification (no JavaScript-specific tags, e.g. !!js/regexp).


safeLoadAll (string, iterator [ , options ])

Same as loadAll() but uses SAFE_SCHEMA by default - only recommended tags of
YAML specification (no JavaScript-specific tags, e.g. !!js/regexp).


dump (object [ , options ])

Serializes object as YAML document.

options:


indent (default: 2) - indentation width to use (in spaces).

flowLevel (default: -1) - specifies level of nesting, when to switch from
block to flow style for collections. -1 means block style everwhere

styles - "tag" => "style" map. Each tag may have own set of styles.

schema (default: DEFAULT_SCHEMA) specifies a schema to use.


styles:

!!null
  "canonical"   => "~"

!!int
  "binary"      => "0b1", "0b101010", "0b1110001111010"
  "octal"       => "01", "052", "016172"
  "decimal"     => "1", "42", "7290"
  "hexadecimal" => "0x1", "0x2A", "0x1C7A"

!!null, !!bool, !!float
  "lowercase"   => "null", "true", "false", ".nan", '.inf'
  "uppercase"   => "NULL", "TRUE", "FALSE", ".NAN", '.INF'
  "camelcase"   => "Null", "True", "False", ".NaN", '.Inf'


By default, !!int uses decimal, and !!null, !!bool, !!float use lowercase.


safeDump (object [ , options ])

Same as dump() but uses SAFE_SCHEMA by default - only recommended tags of
YAML specification (no JavaScript-specific tags, e.g. !!js/regexp).


Supported YAML types

The list of standard YAML tags and corresponding JavaScipt types. See also
YAML tag discussion and
YAML types repository.

!!null ''                   # null
!!bool 'yes'                # bool
!!int '3...'                # number
!!float '3.14...'           # number
!!binary '...base64...'     # buffer
!!timestamp 'YYYY-...'      # date
!!omap [ ... ]              # array of key-value pairs
!!pairs [ ... ]             # array or array pairs
!!set { ... }               # array of objects with given keys and null values
!!str '...'                 # string
!!seq [ ... ]               # array
!!map { ... }               # object


JavaScript-specific tags

!!js/regexp /pattern/gim            # RegExp
!!js/undefined ''                   # Undefined
!!js/function 'function () {...}'   # Function


Caveats

Note, that you use arrays or objects as key in JS-YAML. JS do not allows objects
or array as keys, and stringifies (by calling .toString method) them at the
moment of adding them.

---
? [ foo, bar ]
: - baz
? { foo: bar }
: - baz
  - baz


{ "foo,bar": ["baz"], "[object Object]": ["baz", "baz"] }


Also, reading of properties on implicit block mapping keys is not supported yet.
So, the following YAML document cannot be loaded.

&anchor foo:
  foo: bar
  *anchor: duplicate key
  baz: bat
  *anchor: duplicate key


License

View the LICENSE file
(MIT).