js-yaml vs front-matter vs yamljs vs gray-matter vs yaml-front-matter
Markdown Front Matter Parsing Libraries Comparison
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What's Markdown Front Matter Parsing Libraries?

These libraries are designed to parse front matter from Markdown files, allowing developers to extract metadata and configuration settings from the top of Markdown documents. This is particularly useful in static site generators and content management systems where metadata is often used to control how content is displayed or processed. Each library offers unique features and syntax support, catering to different use cases and preferences in handling YAML and front matter formats.

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js-yaml101,132,4686,366-654 years agoMIT
front-matter2,597,953681-305 years agoMIT
yamljs1,953,101888-538 years agoMIT
gray-matter1,696,0274,066-664 years agoMIT
yaml-front-matter115,454193-204 years agoMIT
Feature Comparison: js-yaml vs front-matter vs yamljs vs gray-matter vs yaml-front-matter

Parsing Capabilities

  • js-yaml:

    js-yaml is a powerful YAML parser that can handle complex YAML structures, including nested objects and arrays. It is not specifically designed for front matter but is excellent for general YAML parsing needs.

  • front-matter:

    front-matter provides a simple API to extract front matter from Markdown files. It supports basic YAML syntax and is optimized for performance, making it ideal for projects that require minimal overhead.

  • yamljs:

    yamljs is a comprehensive library for parsing and stringifying YAML. It supports advanced YAML features and is suitable for applications that require extensive manipulation of YAML data.

  • gray-matter:

    gray-matter excels in parsing both YAML and JSON front matter, offering flexibility with custom delimiters. It also allows you to parse the content of the Markdown file alongside the front matter, which is useful for static site generators.

  • yaml-front-matter:

    yaml-front-matter combines YAML parsing with front matter extraction, allowing you to easily manage metadata in Markdown files. It provides a straightforward API for accessing front matter and the remaining content of the Markdown file.

Ease of Use

  • js-yaml:

    js-yaml has a slightly steeper learning curve due to its extensive features, but it is well-documented, making it manageable for developers who need advanced YAML capabilities.

  • front-matter:

    front-matter is designed for simplicity, making it easy to integrate into projects without a steep learning curve. Its API is intuitive, allowing developers to quickly extract front matter with minimal configuration.

  • yamljs:

    yamljs is powerful but may require more effort to learn due to its comprehensive feature set. However, it provides detailed documentation to assist developers in utilizing its capabilities.

  • gray-matter:

    gray-matter offers a user-friendly API that is easy to understand, especially for those familiar with Markdown. Its ability to handle different front matter formats makes it versatile for various projects.

  • yaml-front-matter:

    yaml-front-matter is straightforward to use, providing clear methods for extracting front matter and content. Its API is designed to be intuitive for developers working with Markdown.

Performance

  • js-yaml:

    js-yaml is robust but may not be as fast as lighter libraries for simple front matter parsing. It is best used when complex YAML structures are involved, where its performance trade-offs are justified.

  • front-matter:

    front-matter is lightweight and optimized for performance, making it suitable for high-frequency parsing scenarios, such as in static site generators where speed is crucial.

  • yamljs:

    yamljs is designed for comprehensive YAML handling, which may introduce some performance overhead compared to simpler libraries. It is best used when advanced YAML features are needed.

  • gray-matter:

    gray-matter balances performance with flexibility, allowing for efficient parsing of front matter while also supporting additional features without significant overhead.

  • yaml-front-matter:

    yaml-front-matter performs well for typical front matter extraction tasks, but its performance may vary based on the complexity of the YAML content being parsed.

Community and Support

  • js-yaml:

    js-yaml has a strong community and extensive documentation, making it a reliable choice for developers needing support for YAML parsing.

  • front-matter:

    front-matter has a smaller community compared to some alternatives, but it is actively maintained and sufficient for basic needs.

  • yamljs:

    yamljs has a solid community and is well-documented, providing ample resources for developers seeking help with YAML parsing and manipulation.

  • gray-matter:

    gray-matter enjoys a larger user base and community support, making it easier to find examples and solutions to common issues.

  • yaml-front-matter:

    yaml-front-matter has a decent level of community support, with documentation that covers most use cases, although it may not be as extensive as larger libraries.

Extensibility

  • js-yaml:

    js-yaml is highly extensible, allowing developers to define custom YAML types and tags, making it suitable for complex applications that require tailored YAML handling.

  • front-matter:

    front-matter is minimalistic and does not offer extensibility features, focusing solely on front matter parsing without additional functionalities.

  • yamljs:

    yamljs is very extensible, supporting custom YAML types and advanced features, making it a great choice for projects that require extensive YAML manipulation.

  • gray-matter:

    gray-matter allows for some extensibility through custom delimiters and the ability to parse different content types, making it adaptable for various use cases.

  • yaml-front-matter:

    yaml-front-matter provides basic extensibility for front matter management but is primarily focused on simplicity and ease of use.

How to Choose: js-yaml vs front-matter vs yamljs vs gray-matter vs yaml-front-matter
  • js-yaml:

    Select js-yaml if your primary need is robust YAML parsing and stringifying, especially if you require advanced YAML features like support for complex data types or custom YAML tags, and you don't specifically need front matter parsing.

  • front-matter:

    Choose front-matter if you need a lightweight and straightforward library that focuses solely on parsing front matter from Markdown files without any additional dependencies or complexity.

  • yamljs:

    Choose yamljs if you need a comprehensive YAML parser and serializer that can handle complex YAML structures, and you want the flexibility to work with YAML data beyond just front matter.

  • gray-matter:

    Opt for gray-matter if you want a more versatile solution that can handle both YAML and JSON front matter, and provides additional features like custom delimiters and the ability to parse Markdown content along with the front matter.

  • yaml-front-matter:

    Use yaml-front-matter if you prefer a library that combines YAML parsing with front matter extraction, and you want a simple API that allows you to easily manage front matter in your Markdown files.

Similar Npm Packages to js-yaml

js-yaml is a popular JavaScript library for parsing and dumping YAML (YAML Ain't Markup Language) data. It allows developers to easily convert YAML data into JavaScript objects and vice versa, making it a valuable tool for applications that require configuration files or data serialization in YAML format. While js-yaml is widely used, there are several alternatives in the ecosystem that also provide YAML parsing and manipulation capabilities. Here are a few notable alternatives:

  • yaml is a modern YAML parser and serializer for JavaScript. It aims to provide a more robust and feature-rich alternative to js-yaml, with support for advanced YAML features and better performance. The library is designed to be easy to use and integrates well with both Node.js and browser environments. If you are looking for a library that offers more features and better performance for handling YAML data, yaml is a great option.
  • yaml-front-matter is a specialized library that focuses on parsing YAML front matter, which is commonly used in static site generators like Jekyll and Gatsby. This library allows developers to easily extract front matter from documents, making it particularly useful for managing metadata in markdown files. If your project involves working with markdown files that include YAML front matter, yaml-front-matter is a convenient choice.
  • yamljs is another library for parsing and dumping YAML in JavaScript. It offers a simple API for converting YAML to JavaScript objects and vice versa. While it may not have as many features as some of the other libraries, it is lightweight and easy to use, making it suitable for smaller projects or applications that require basic YAML functionality.

For a detailed comparison of these libraries, check out the link: Comparing js-yaml vs yaml vs yaml-front-matter vs yamljs.

Similar Npm Packages to front-matter

front-matter is a lightweight npm package designed for parsing front matter from files, typically used in static site generators and content management systems. Front matter refers to the metadata that is placed at the top of a file, often in YAML or TOML format, which provides information about the content such as title, date, tags, and more. The front-matter package allows developers to easily extract this metadata from their files, making it a valuable tool for managing content in a structured way.

While front-matter is a popular choice, there are other libraries that offer similar functionality. Here are a few alternatives:

  • gray-matter is a widely used library for parsing front matter from Markdown and other text files. It supports multiple formats, including YAML, TOML, and JSON, making it versatile for various use cases. gray-matter not only extracts the front matter but also returns the content of the file without the metadata, allowing for easy integration into static site generators and other applications. If you need a robust solution that can handle different front matter formats, gray-matter is an excellent choice.
  • yaml-front-matter is another library focused specifically on parsing YAML front matter. It provides a straightforward API for extracting metadata from files that use YAML format for their front matter. If your project primarily uses YAML and you want a dedicated solution for handling it, yaml-front-matter is a lightweight and efficient option.

To see how front-matter compares with gray-matter and yaml-front-matter, check out the comparison: Comparing front-matter vs gray-matter vs yaml-front-matter.

Similar Npm Packages to yamljs

yamljs is a JavaScript library that allows developers to parse and stringify YAML (YAML Ain't Markup Language) files easily. It provides a straightforward API for working with YAML data, making it a popular choice for applications that require configuration files or data interchange in a human-readable format. While yamljs is a solid option for handling YAML, there are other libraries available that also serve this purpose. Here are a few alternatives:

  • js-yaml is a widely used library for parsing and dumping YAML in JavaScript. It is known for its performance and flexibility, supporting both Node.js and browser environments. js-yaml is particularly useful for developers who need to work with YAML in various contexts, such as server-side applications or client-side scripts. Its robust feature set and active community make it a reliable choice for handling YAML data.
  • yaml is another modern YAML parser and serializer for JavaScript. It aims to provide a more complete and user-friendly interface compared to other libraries. yaml supports advanced features such as custom types and schema validation, making it suitable for complex applications that require more than just basic YAML parsing and stringification. If you need a library that offers both simplicity and advanced capabilities, yaml is an excellent option.

To see how yamljs compares with js-yaml and yaml, check out the comparison: Comparing js-yaml vs yaml vs yamljs.

Similar Npm Packages to gray-matter

gray-matter is a popular npm package used for parsing front matter from Markdown files. Front matter is a section at the beginning of a Markdown document that contains metadata about the content, typically formatted in YAML or JSON. gray-matter allows developers to easily extract this metadata and separate it from the actual content, making it a valuable tool for static site generators and content management systems. Its ability to handle various formats and its straightforward API make it a go-to choice for many developers working with Markdown.

While gray-matter is a solid choice for parsing front matter, there are several alternatives that offer similar functionality:

  • front-matter is a lightweight library that focuses specifically on parsing front matter from Markdown files. It provides a simple API for extracting the metadata and content from the document. If you are looking for a minimalistic solution without additional features, front-matter is a great option that offers straightforward parsing capabilities.
  • remark-frontmatter is a plugin for the remark Markdown processor that allows you to work with front matter in Markdown files. It integrates seamlessly with the remark ecosystem, making it a good choice if you are already using remark for processing Markdown. This plugin enables you to parse front matter while leveraging the full power of remark for transforming Markdown content.
  • yaml-front-matter is another alternative that specifically focuses on parsing YAML front matter. It provides a simple API for extracting metadata from YAML-formatted front matter in Markdown files. If your project primarily uses YAML for front matter and you want a dedicated solution, yaml-front-matter is an excellent choice.

To see how these packages compare, check out the comparison: Comparing front-matter vs gray-matter vs remark-frontmatter vs yaml-front-matter.

Similar Npm Packages to yaml-front-matter

yaml-front-matter is a JavaScript library designed to parse YAML front matter from text files. Front matter is a common pattern used in static site generators and content management systems, where metadata is defined at the beginning of a file, typically in YAML format. This library allows developers to easily extract this metadata and the content of the file, making it a useful tool for managing structured data in markdown or other text-based formats.

While yaml-front-matter is a robust option for handling YAML front matter, there are several alternatives worth considering:

  • front-matter is a simple library that extracts front matter from markdown files. It supports both YAML and JSON formats, making it versatile for different use cases. If you're looking for a straightforward solution to parse front matter without the need for YAML-specific features, front-matter is a solid choice.
  • gray-matter is another popular library for parsing front matter, supporting multiple formats including YAML, JSON, and TOML. It is widely used in static site generators like Gatsby and Next.js. gray-matter provides additional features such as the ability to customize delimiters and parse front matter from various file types, making it a flexible option for developers who need more control over their front matter parsing.
  • js-yaml is a YAML parser and dumper for JavaScript. While it is not specifically designed for front matter, it can be used in conjunction with other libraries to handle YAML data. If your project requires extensive YAML parsing capabilities beyond just front matter, js-yaml is a powerful tool that can meet those needs.
  • yamljs is another library for parsing and dumping YAML in JavaScript. Similar to js-yaml, it is not specifically focused on front matter but can be used to work with YAML data in various contexts. If you need a lightweight library for general YAML handling, yamljs is a good option.

To compare these packages and find the best fit for your project, check out the comparison link: Comparing front-matter vs gray-matter vs js-yaml vs yaml-front-matter vs yamljs.

README for js-yaml

JS-YAML - YAML 1.2 parser / writer for JavaScript

CI NPM version

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 -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 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);
}

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: http://www.yaml.org/spec/1.2/spec.html#id2802346
    • JSON_SCHEMA - all JSON-supported types: http://www.yaml.org/spec/1.2/spec.html#id2803231
    • CORE_SCHEMA - same as JSON_SCHEMA: http://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.

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 ->:

!!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
});

Supported YAML types

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.

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.

---
? [ 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

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