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.
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 safeLoad()
on fetched content of a file. Just with one string!
require('js-yaml');
try {
var doc = require('/home/ixti/example.yml');
console.log(doc);
} catch (e) {
console.log(e);
}
safeLoad (string [ , options ])
Recommended loading way. Parses string
as single YAML document. Returns a JavaScript
object or throws YAMLException
on error. By default, does not support regexps,
functions and undefined. This method is safe for untrusted data.
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_SAFE_SCHEMA
) - specifies a schema to use.
NOTE: This function does not understand multi-document sources, it throws
exception on those.
NOTE: JS-YAML does not support schema-specific tag resolution restrictions.
So, JSON schema is not such strict as defined in the YAML specification.
It allows numbers in any notaion, use Null
and NULL
as null
, etc.
Core schema also has no such restrictions. It allows binary notation for integers.
load (string [ , options ])
Use with care with untrusted sources. The same as safeLoad()
but uses
DEFAULT_FULL_SCHEMA
by default - adds some JavaScript-specific types:
!!js/function
, !!js/regexp
and !!js/undefined
. For untrusted sources you
must additionally validate object structure, to avoid injections:
var untrusted_code = '"toString": !<tag:yaml.org,2002:js/function> "function (){very_evil_thing();}"';
require('js-yaml').load(untrusted_code) + ''
safeLoadAll (string, iterator [ , options ])
Same as safeLoad()
, but understands multi-document sources and apply
iterator
to each document.
var yaml = require('js-yaml');
yaml.safeLoadAll(data, function (doc) {
console.log(doc);
});
loadAll (string, iterator [ , options ])
Same as safeLoadAll()
but uses DEFAULT_FULL_SCHEMA
by default.
safeDump (object [ , options ])
Serializes object
as YAML document. Uses DEFAULT_SAFE_SCHEMA
, so it will
throw exception if you try to dump regexps or functions. However, you can
disable exceptions by skipInvalid
option.
options:
indent
(default: 2) - indentation width to use (in spaces).skipInvalid
(default: false) - do not throw on invalid types (like function
in the safe schema) and skip pairs and single values with such types.flowLevel
(default: -1) - specifies level of nesting, when to switch from
block to flow style for collections. -1 means block style everwherestyles
- "tag" => "style" map. Each tag may have own set of styles.schema
(default: DEFAULT_SAFE_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
.
dump (object [ , options ])
Same as safeDump()
but without limits (uses DEFAULT_FULL_SCHEMA
by default).
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
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.
License
View the LICENSE file
(MIT).