forked from actions/setup-maven
315 lines
9.9 KiB
Markdown
315 lines
9.9 KiB
Markdown
JS-YAML - YAML 1.2 parser / writer for JavaScript
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=================================================
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[](https://travis-ci.org/nodeca/js-yaml)
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[](https://www.npmjs.org/package/js-yaml)
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__[Online Demo](http://nodeca.github.com/js-yaml/)__
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This is an implementation of [YAML](http://yaml.org/), a human-friendly data
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serialization language. Started as [PyYAML](http://pyyaml.org/) port, it was
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completely rewritten from scratch. Now it's very fast, and supports 1.2 spec.
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Installation
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------------
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### YAML module for node.js
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```
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npm install js-yaml
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```
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### CLI executable
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If you want to inspect your YAML files from CLI, install js-yaml globally:
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```
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npm install -g js-yaml
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```
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#### Usage
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```
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usage: js-yaml [-h] [-v] [-c] [-t] file
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Positional arguments:
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file File with YAML document(s)
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Optional arguments:
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-h, --help Show this help message and exit.
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-v, --version Show program's version number and exit.
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-c, --compact Display errors in compact mode
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-t, --trace Show stack trace on error
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```
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### Bundled YAML library for browsers
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``` html
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<!-- esprima required only for !!js/function -->
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<script src="esprima.js"></script>
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<script src="js-yaml.min.js"></script>
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<script type="text/javascript">
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var doc = jsyaml.load('greeting: hello\nname: world');
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</script>
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```
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Browser support was done mostly for the online demo. If you find any errors - feel
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free to send pull requests with fixes. Also note, that IE and other old browsers
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needs [es5-shims](https://github.com/kriskowal/es5-shim) to operate.
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Notes:
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1. We have no resources to support browserified version. Don't expect it to be
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well tested. Don't expect fast fixes if something goes wrong there.
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2. `!!js/function` in browser bundle will not work by default. If you really need
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it - load `esprima` parser first (via amd or directly).
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3. `!!bin` in browser will return `Array`, because browsers do not support
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node.js `Buffer` and adding Buffer shims is completely useless on practice.
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API
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---
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Here we cover the most 'useful' methods. If you need advanced details (creating
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your own tags), see [wiki](https://github.com/nodeca/js-yaml/wiki) and
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[examples](https://github.com/nodeca/js-yaml/tree/master/examples) for more
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info.
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``` javascript
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yaml = require('js-yaml');
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fs = require('fs');
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// Get document, or throw exception on error
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try {
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var doc = yaml.safeLoad(fs.readFileSync('/home/ixti/example.yml', 'utf8'));
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console.log(doc);
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} catch (e) {
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console.log(e);
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}
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```
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### safeLoad (string [ , options ])
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**Recommended loading way.** Parses `string` as single YAML document. Returns a JavaScript
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object or throws `YAMLException` on error. By default, does not support regexps,
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functions and undefined. This method is safe for untrusted data.
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options:
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- `filename` _(default: null)_ - string to be used as a file path in
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error/warning messages.
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- `onWarning` _(default: null)_ - function to call on warning messages.
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Loader will call this function with an instance of `YAMLException` for each warning.
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- `schema` _(default: `DEFAULT_SAFE_SCHEMA`)_ - specifies a schema to use.
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- `FAILSAFE_SCHEMA` - only strings, arrays and plain objects:
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http://www.yaml.org/spec/1.2/spec.html#id2802346
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- `JSON_SCHEMA` - all JSON-supported types:
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http://www.yaml.org/spec/1.2/spec.html#id2803231
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- `CORE_SCHEMA` - same as `JSON_SCHEMA`:
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http://www.yaml.org/spec/1.2/spec.html#id2804923
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- `DEFAULT_SAFE_SCHEMA` - all supported YAML types, without unsafe ones
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(`!!js/undefined`, `!!js/regexp` and `!!js/function`):
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http://yaml.org/type/
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- `DEFAULT_FULL_SCHEMA` - all supported YAML types.
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- `json` _(default: false)_ - compatibility with JSON.parse behaviour. If true, then duplicate keys in a mapping will override values rather than throwing an error.
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NOTE: This function **does not** understand multi-document sources, it throws
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exception on those.
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NOTE: JS-YAML **does not** support schema-specific tag resolution restrictions.
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So, the JSON schema is not as strictly defined in the YAML specification.
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It allows numbers in any notation, use `Null` and `NULL` as `null`, etc.
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The core schema also has no such restrictions. It allows binary notation for integers.
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### load (string [ , options ])
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**Use with care with untrusted sources**. The same as `safeLoad()` but uses
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`DEFAULT_FULL_SCHEMA` by default - adds some JavaScript-specific types:
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`!!js/function`, `!!js/regexp` and `!!js/undefined`. For untrusted sources, you
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must additionally validate object structure to avoid injections:
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``` javascript
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var untrusted_code = '"toString": !<tag:yaml.org,2002:js/function> "function (){very_evil_thing();}"';
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// I'm just converting that string, what could possibly go wrong?
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require('js-yaml').load(untrusted_code) + ''
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```
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### safeLoadAll (string [, iterator] [, options ])
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Same as `safeLoad()`, but understands multi-document sources. Applies
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`iterator` to each document if specified, or returns array of documents.
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``` javascript
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var yaml = require('js-yaml');
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yaml.safeLoadAll(data, function (doc) {
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console.log(doc);
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});
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```
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### loadAll (string [, iterator] [ , options ])
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Same as `safeLoadAll()` but uses `DEFAULT_FULL_SCHEMA` by default.
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### safeDump (object [ , options ])
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Serializes `object` as a YAML document. Uses `DEFAULT_SAFE_SCHEMA`, so it will
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throw an exception if you try to dump regexps or functions. However, you can
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disable exceptions by setting the `skipInvalid` option to `true`.
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options:
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- `indent` _(default: 2)_ - indentation width to use (in spaces).
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- `noArrayIndent` _(default: false)_ - when true, will not add an indentation level to array elements
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- `skipInvalid` _(default: false)_ - do not throw on invalid types (like function
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in the safe schema) and skip pairs and single values with such types.
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- `flowLevel` (default: -1) - specifies level of nesting, when to switch from
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block to flow style for collections. -1 means block style everwhere
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- `styles` - "tag" => "style" map. Each tag may have own set of styles.
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- `schema` _(default: `DEFAULT_SAFE_SCHEMA`)_ specifies a schema to use.
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- `sortKeys` _(default: `false`)_ - if `true`, sort keys when dumping YAML. If a
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function, use the function to sort the keys.
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- `lineWidth` _(default: `80`)_ - set max line width.
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- `noRefs` _(default: `false`)_ - if `true`, don't convert duplicate objects into references
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- `noCompatMode` _(default: `false`)_ - if `true` don't try to be compatible with older
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yaml versions. Currently: don't quote "yes", "no" and so on, as required for YAML 1.1
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- `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.
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The following table show availlable styles (e.g. "canonical",
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"binary"...) available for each tag (.e.g. !!null, !!int ...). Yaml
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output is shown on the right side after `=>` (default setting) or `->`:
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``` none
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!!null
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"canonical" -> "~"
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"lowercase" => "null"
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"uppercase" -> "NULL"
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"camelcase" -> "Null"
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!!int
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"binary" -> "0b1", "0b101010", "0b1110001111010"
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"octal" -> "01", "052", "016172"
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"decimal" => "1", "42", "7290"
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"hexadecimal" -> "0x1", "0x2A", "0x1C7A"
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!!bool
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"lowercase" => "true", "false"
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"uppercase" -> "TRUE", "FALSE"
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"camelcase" -> "True", "False"
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!!float
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"lowercase" => ".nan", '.inf'
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"uppercase" -> ".NAN", '.INF'
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"camelcase" -> ".NaN", '.Inf'
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```
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Example:
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``` javascript
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safeDump (object, {
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'styles': {
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'!!null': 'canonical' // dump null as ~
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},
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'sortKeys': true // sort object keys
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});
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```
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### dump (object [ , options ])
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Same as `safeDump()` but without limits (uses `DEFAULT_FULL_SCHEMA` by default).
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Supported YAML types
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--------------------
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The list of standard YAML tags and corresponding JavaScipt types. See also
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[YAML tag discussion](http://pyyaml.org/wiki/YAMLTagDiscussion) and
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[YAML types repository](http://yaml.org/type/).
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```
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!!null '' # null
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!!bool 'yes' # bool
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!!int '3...' # number
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!!float '3.14...' # number
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!!binary '...base64...' # buffer
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!!timestamp 'YYYY-...' # date
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!!omap [ ... ] # array of key-value pairs
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!!pairs [ ... ] # array or array pairs
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!!set { ... } # array of objects with given keys and null values
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!!str '...' # string
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!!seq [ ... ] # array
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!!map { ... } # object
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```
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**JavaScript-specific tags**
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```
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!!js/regexp /pattern/gim # RegExp
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!!js/undefined '' # Undefined
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!!js/function 'function () {...}' # Function
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```
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Caveats
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-------
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Note, that you use arrays or objects as key in JS-YAML. JS does not allow objects
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or arrays as keys, and stringifies (by calling `toString()` method) them at the
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moment of adding them.
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``` yaml
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---
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? [ foo, bar ]
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: - baz
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? { foo: bar }
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: - baz
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- baz
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```
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``` javascript
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{ "foo,bar": ["baz"], "[object Object]": ["baz", "baz"] }
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```
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Also, reading of properties on implicit block mapping keys is not supported yet.
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So, the following YAML document cannot be loaded.
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``` yaml
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&anchor foo:
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foo: bar
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*anchor: duplicate key
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baz: bat
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*anchor: duplicate key
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```
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Breaking changes in 2.x.x -> 3.x.x
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----------------------------------
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If you have not used __custom__ tags or loader classes and not loaded yaml
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files via `require()`, no changes are needed. Just upgrade the library.
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Otherwise, you should:
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1. Replace all occurrences of `require('xxxx.yml')` by `fs.readFileSync()` +
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`yaml.safeLoad()`.
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2. rewrite your custom tags constructors and custom loader
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classes, to conform the new API. See
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[examples](https://github.com/nodeca/js-yaml/tree/master/examples) and
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[wiki](https://github.com/nodeca/js-yaml/wiki) for details.
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License
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-------
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View the [LICENSE](https://github.com/nodeca/js-yaml/blob/master/LICENSE) file
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(MIT).
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