156 lines
5.9 KiB
Markdown
156 lines
5.9 KiB
Markdown
# YAML <a href="https://www.npmjs.com/package/yaml"><img align="right" src="https://badge.fury.io/js/yaml.svg" title="npm package" /></a>
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`yaml` is a definitive library for [YAML](https://yaml.org/), the human friendly data serialization standard.
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This library:
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- Supports both YAML 1.1 and YAML 1.2 and all common data schemas,
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- Passes all of the [yaml-test-suite](https://github.com/yaml/yaml-test-suite) tests,
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- Can accept any string as input without throwing, parsing as much YAML out of it as it can, and
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- Supports parsing, modifying, and writing YAML comments and blank lines.
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The library is released under the ISC open source license, and the code is [available on GitHub](https://github.com/eemeli/yaml/).
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It has no external dependencies and runs on Node.js as well as modern browsers.
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For the purposes of versioning, any changes that break any of the documented endpoints or APIs will be considered semver-major breaking changes.
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Undocumented library internals may change between minor versions, and previous APIs may be deprecated (but not removed).
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The minimum supported TypeScript version of the included typings is 3.9;
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for use in earlier versions you may need to set `skipLibCheck: true` in your config.
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This requirement may be updated between minor versions of the library.
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For more information, see the project's documentation site: [**eemeli.org/yaml**](https://eemeli.org/yaml/)
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To install:
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```sh
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npm install yaml
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```
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**Note:** These docs are for `yaml@2`. For v1, see the [v1.10.0 tag](https://github.com/eemeli/yaml/tree/v1.10.0) for the source and [eemeli.org/yaml/v1](https://eemeli.org/yaml/v1/) for the documentation.
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The development and maintenance of this library is [sponsored](https://github.com/sponsors/eemeli) by:
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<a href="https://www.scipress.io/">
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<img width=150 src="https://eemeli.org/yaml/images/scipress.svg" alt="Scipress" />
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</a>
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## API Overview
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The API provided by `yaml` has three layers, depending on how deep you need to go: [Parse & Stringify](https://eemeli.org/yaml/#parse-amp-stringify), [Documents](https://eemeli.org/yaml/#documents), and the underlying [Lexer/Parser/Composer](https://eemeli.org/yaml/#parsing-yaml).
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The first has the simplest API and "just works", the second gets you all the bells and whistles supported by the library along with a decent [AST](https://eemeli.org/yaml/#content-nodes), and the third lets you get progressively closer to YAML source, if that's your thing.
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A [command-line tool](https://eemeli.org/yaml/#command-line-tool) is also included.
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```js
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import { parse, stringify } from 'yaml'
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// or
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import YAML from 'yaml'
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// or
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const YAML = require('yaml')
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```
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### Parse & Stringify
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- [`parse(str, reviver?, options?): value`](https://eemeli.org/yaml/#yaml-parse)
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- [`stringify(value, replacer?, options?): string`](https://eemeli.org/yaml/#yaml-stringify)
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### Documents
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- [`Document`](https://eemeli.org/yaml/#documents)
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- [`constructor(value, replacer?, options?)`](https://eemeli.org/yaml/#creating-documents)
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- [`#anchors`](https://eemeli.org/yaml/#working-with-anchors)
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- [`#contents`](https://eemeli.org/yaml/#content-nodes)
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- [`#directives`](https://eemeli.org/yaml/#stream-directives)
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- [`#errors`](https://eemeli.org/yaml/#errors)
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- [`#warnings`](https://eemeli.org/yaml/#errors)
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- [`isDocument(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`parseAllDocuments(str, options?): Document[]`](https://eemeli.org/yaml/#parsing-documents)
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- [`parseDocument(str, options?): Document`](https://eemeli.org/yaml/#parsing-documents)
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### Content Nodes
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- [`isAlias(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isCollection(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isMap(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isNode(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isPair(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isScalar(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`isSeq(foo): boolean`](https://eemeli.org/yaml/#identifying-node-types)
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- [`new Scalar(value)`](https://eemeli.org/yaml/#scalar-values)
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- [`new YAMLMap()`](https://eemeli.org/yaml/#collections)
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- [`new YAMLSeq()`](https://eemeli.org/yaml/#collections)
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- [`doc.createAlias(node, name?): Alias`](https://eemeli.org/yaml/#working-with-anchors)
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- [`doc.createNode(value, options?): Node`](https://eemeli.org/yaml/#creating-nodes)
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- [`doc.createPair(key, value): Pair`](https://eemeli.org/yaml/#creating-nodes)
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- [`visit(node, visitor)`](https://eemeli.org/yaml/#finding-and-modifying-nodes)
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### Parsing YAML
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- [`new Lexer().lex(src)`](https://eemeli.org/yaml/#lexer)
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- [`new Parser(onNewLine?).parse(src)`](https://eemeli.org/yaml/#parser)
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- [`new Composer(options?).compose(tokens)`](https://eemeli.org/yaml/#composer)
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## YAML.parse
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```yaml
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# file.yml
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YAML:
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- A human-readable data serialization language
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- https://en.wikipedia.org/wiki/YAML
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yaml:
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- A complete JavaScript implementation
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- https://www.npmjs.com/package/yaml
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```
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```js
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import fs from 'fs'
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import YAML from 'yaml'
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YAML.parse('3.14159')
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// 3.14159
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YAML.parse('[ true, false, maybe, null ]\n')
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// [ true, false, 'maybe', null ]
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const file = fs.readFileSync('./file.yml', 'utf8')
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YAML.parse(file)
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// { YAML:
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// [ 'A human-readable data serialization language',
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// 'https://en.wikipedia.org/wiki/YAML' ],
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// yaml:
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// [ 'A complete JavaScript implementation',
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// 'https://www.npmjs.com/package/yaml' ] }
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```
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## YAML.stringify
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```js
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import YAML from 'yaml'
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YAML.stringify(3.14159)
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// '3.14159\n'
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YAML.stringify([true, false, 'maybe', null])
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// `- true
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// - false
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// - maybe
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// - null
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// `
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YAML.stringify({ number: 3, plain: 'string', block: 'two\nlines\n' })
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// `number: 3
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// plain: string
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// block: |
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// two
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// lines
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// `
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```
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---
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Browser testing provided by:
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<a href="https://www.browserstack.com/open-source">
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<img width=200 src="https://eemeli.org/yaml/images/browserstack.svg" alt="BrowserStack" />
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</a>
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