Security News
Internet Archive Hacked, 31 Million Record Compromised
The Internet Archive's "Wayback Machine" has been hacked and defaced, with 31 millions records compromised.
@zkochan/js-yaml
Advanced tools
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.
npm install js-yaml
If you want to inspect your YAML files from CLI, install js-yaml globally:
npm install -g js-yaml
usage: js-yaml [-h] [-v] [-c] [-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
-t, --trace Show stack trace on error
Here we cover the most 'useful' methods. If you need advanced details (creating your own tags), see examples for more info.
const yaml = require('js-yaml');
const fs = require('fs');
// Get document, or throw exception on error
try {
const doc = yaml.load(fs.readFileSync('/home/ixti/example.yml', 'utf8'));
console.log(doc);
} catch (e) {
console.log(e);
}
Parses string
as single YAML document. Returns either a
plain object, a string, a number, null
or undefined
, or throws YAMLException
on error. By default, does
not support regexps, functions and undefined.
options:
filename
(default: null) - string to be used as a file path in
error/warning messages.onWarning
(default: null) - function to call on warning messages.
Loader will call this function with an instance of YAMLException
for each warning.schema
(default: DEFAULT_SCHEMA
) - specifies a schema to use.
FAILSAFE_SCHEMA
- only strings, arrays and plain objects:
http://www.yaml.org/spec/1.2/spec.html#id2802346JSON_SCHEMA
- all JSON-supported types:
http://www.yaml.org/spec/1.2/spec.html#id2803231CORE_SCHEMA
- same as JSON_SCHEMA
:
http://www.yaml.org/spec/1.2/spec.html#id2804923DEFAULT_SCHEMA
- all supported YAML types.json
(default: false) - compatibility with JSON.parse behaviour. If true, then duplicate keys in a mapping will override values rather than throwing an error.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, the JSON schema is not as strictly defined in the YAML specification.
It allows numbers in any notation, use Null
and NULL
as null
, etc.
The core schema also has no such restrictions. It allows binary notation for integers.
Same as load()
, but understands multi-document sources. Applies
iterator
to each document if specified, or returns array of documents.
const yaml = require('js-yaml');
yaml.loadAll(data, function (doc) {
console.log(doc);
});
Serializes object
as a YAML document. Uses DEFAULT_SCHEMA
, so it will
throw an exception if you try to dump regexps or functions. However, you can
disable exceptions by setting the skipInvalid
option to true
.
options:
indent
(default: 2) - indentation width to use (in spaces).noArrayIndent
(default: false) - when true, will not add an indentation level to array elementsskipInvalid
(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_SCHEMA
) specifies a schema to use.sortKeys
(default: false
) - if true
, sort keys when dumping YAML. If a
function, use the function to sort the keys.lineWidth
(default: 80
) - set max line width.noRefs
(default: false
) - if true
, don't convert duplicate objects into referencesnoCompatMode
(default: false
) - if true
don't try to be compatible with older
yaml versions. Currently: don't quote "yes", "no" and so on, as required for YAML 1.1condenseFlow
(default: false
) - if true
flow sequences will be condensed, omitting the space between a, b
. Eg. '[a,b]'
, and omitting the space between key: value
and quoting the key. Eg. '{"a":b}'
Can be useful when using yaml for pretty URL query params as spaces are %-encoded.quotingType
('
or "
, default: '
) - strings will be quoted using this quoting style. If you specify single quotes, double quotes will still be used for non-printable characters.forceQuotes
(default: false
) - if true
, all non-key strings will be quoted even if they normally don't need to.replacer
- callback function (key, value)
called recursively on each key/value in source object (see replacer
docs for JSON.stringify
).The following table show availlable styles (e.g. "canonical",
"binary"...) available for each tag (.e.g. !!null, !!int ...). Yaml
output is shown on the right side after =>
(default setting) or ->
:
!!null
"canonical" -> "~"
"lowercase" => "null"
"uppercase" -> "NULL"
"camelcase" -> "Null"
!!int
"binary" -> "0b1", "0b101010", "0b1110001111010"
"octal" -> "0o1", "0o52", "0o16172"
"decimal" => "1", "42", "7290"
"hexadecimal" -> "0x1", "0x2A", "0x1C7A"
!!bool
"lowercase" => "true", "false"
"uppercase" -> "TRUE", "FALSE"
"camelcase" -> "True", "False"
!!float
"lowercase" => ".nan", '.inf'
"uppercase" -> ".NAN", '.INF'
"camelcase" -> ".NaN", '.Inf'
Example:
dump(object, {
'styles': {
'!!null': 'canonical' // dump null as ~
},
'sortKeys': true // sort object keys
});
The list of standard YAML tags and corresponding JavaScript 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
See js-yaml-js-types for extra types.
Note, that you use arrays or objects as key in JS-YAML. JS does not allow objects
or arrays 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
Available as part of the Tidelift Subscription
The maintainers of js-yaml and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.
FAQs
YAML 1.2 parser and serializer
The npm package @zkochan/js-yaml receives a total of 2,886,399 weekly downloads. As such, @zkochan/js-yaml popularity was classified as popular.
We found that @zkochan/js-yaml demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
The Internet Archive's "Wayback Machine" has been hacked and defaced, with 31 millions records compromised.
Security News
TC39 is meeting in Tokyo this week and they have approved nearly a dozen proposals to advance to the next stages.
Security News
Our threat research team breaks down two malicious npm packages designed to exploit developer trust, steal your data, and destroy data on your machine.