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https://github.com/nodeca/js-yaml

JavaScript YAML parser and dumper. Very fast.
https://github.com/nodeca/js-yaml

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JavaScript YAML parser and dumper. Very fast.

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README 

        
JS-YAML - YAML 1.2 parser / writer for JavaScript

=================================================



[![CI](https://github.com/nodeca/js-yaml/workflows/CI/badge.svg?branch=master)](https://github.com/nodeca/js-yaml/actions)

[![NPM version](https://img.shields.io/npm/v/js-yaml.svg)](https://www.npmjs.org/package/js-yaml)



__[Online Demo](https://nodeca.github.io/js-yaml/)__



This is an implementation of [YAML](https://yaml.org/), a human-friendly data

serialization language. Started as [PyYAML](https://pyyaml.org/) 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 -g js-yaml

```



#### Usage



```

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

```



API

---



Here we cover the most 'useful' methods. If you need advanced details (creating

your own tags), see [examples](https://github.com/nodeca/js-yaml/tree/master/examples)

for more info.



``` javascript

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);

}

```



### load (string [ , options ])



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:

    https://www.yaml.org/spec/1.2/spec.html#id2802346

  - `JSON_SCHEMA` - all JSON-supported types:

    https://www.yaml.org/spec/1.2/spec.html#id2803231

  - `CORE_SCHEMA` - same as `JSON_SCHEMA`:

    https://www.yaml.org/spec/1.2/spec.html#id2804923

  - `DEFAULT_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.



### loadAll (string [, iterator] [, options ])



Same as `load()`, but understands multi-document sources. Applies

`iterator` to each document if specified, or returns array of documents.



``` javascript

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



yaml.loadAll(data, function (doc) {

  console.log(doc);

});

```



### dump (object [ , options ])



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 elements

- `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 everwhere

- `styles` - "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. Set `-1` for unlimited width.

- `noRefs` _(default: `false`)_ - if `true`, don't convert duplicate objects into references

- `noCompatMode` _(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 1.1

- `condenseFlow` _(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 `->`:



``` none

!!null

  "canonical"   -> "~"

  "lowercase"   => "null"

  "uppercase"   -> "NULL"

  "camelcase"   -> "Null"

  "empty"       -> ""



!!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:



``` javascript

dump(object, {

  'styles': {

    '!!null': 'canonical' // dump null as ~

  },

  'sortKeys': true        // sort object keys

});

```



Supported YAML types

--------------------



The list of standard YAML tags and corresponding JavaScript types. See also

[YAML tag discussion](https://pyyaml.org/wiki/YAMLTagDiscussion) and

[YAML types repository](https://yaml.org/type/).



```

!!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](https://github.com/nodeca/js-yaml-js-types) for

extra types.



Caveats

-------



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.



``` yaml

---

? [ foo, bar ]

: - baz

? { foo: bar }

: - baz

  - baz

```



``` javascript

{ "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.



``` yaml

&anchor foo:

  foo: bar

  *anchor: duplicate key

  baz: bat

  *anchor: duplicate key

```



js-yaml for enterprise

----------------------



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