gray-matter
Advanced tools
Parse front-matter from a string or file. Fast, reliable and easy to use. Parses YAML front matter by default, but also has support for YAML, JSON, TOML or Coffee Front-Matter, with options to set custom delimiters.
The gray-matter npm package is used to parse front-matter from strings or files. Front-matter is metadata stored at the top of a file, typically in YAML or JSON format, which is often used in static site generators and other content management systems.
Parsing Front-Matter
This feature allows you to parse front-matter from a string. The front-matter is typically written in YAML or JSON format and is separated from the content by triple dashes (---). The parsed object contains the metadata and the content separately.
const matter = require('gray-matter');
const file = '---\ntitle: Hello World\ndate: 2023-10-01\n---\nThis is the content of the file.';
const parsed = matter(file);
console.log(parsed);Stringify Front-Matter
This feature allows you to convert a content string and a metadata object back into a string with front-matter. This is useful for generating files with front-matter programmatically.
const matter = require('gray-matter');
const data = { title: 'Hello World', date: '2023-10-01' };
const content = 'This is the content of the file.';
const stringified = matter.stringify(content, data);
console.log(stringified);Custom Delimiters
This feature allows you to specify custom delimiters for the front-matter. By default, gray-matter uses triple dashes (---), but you can change this to any string you prefer.
const matter = require('gray-matter');
const file = '+++\ntitle = "Hello World"\ndate = "2023-10-01"\n+++\nThis is the content of the file.';
const parsed = matter(file, { delimiters: '+++' });
console.log(parsed);The front-matter package is another tool for parsing front-matter from strings. It is simpler and has fewer features compared to gray-matter, but it is also lightweight and easy to use.
The js-yaml package is primarily used for parsing and stringifying YAML, but it can also be used to handle front-matter. It is more general-purpose and powerful for YAML processing, but it requires more setup to use for front-matter specifically.
The marked package is a markdown parser that can also handle front-matter if used in conjunction with other tools. It is more focused on converting markdown to HTML, but it can be extended to support front-matter parsing.
Parse front-matter from a string or file. Fast, reliable and easy to use. Parses YAML front matter by default, but also has support for YAML, JSON, TOML or Coffee Front-Matter, with options to set custom delimiters.
See the benchmarks. gray-matter is 15-30x faster than front-matter.
options.eval is set to trueoptions.eval is set to trueoptions.eval is set to truenpm i gray-matter --save
bower install gray-matter --save
var matter = require('gray-matter');
matter('---\ntitle: Front Matter\n---\nThis is content.');
Returns:
{
orig: '---\ntitle: Front Matter\n---\nThis is content.',
data: { title: 'Front Matter' },
content: '\nThis is content.'
}
That's it! Just pass a string and gray-matter returns an object.
Parses a string of front-matter with the given options, and returns an object.
string {String}: The string to parse.options {Object}
delims {Array}: Custom delimiters formatted as an array. The default is ['---', '---'].parser {Function}: Parser function to use. js-yaml is the default.returns {Object}: Valid JSONmatter('---\ntitle: foo\n---\nbar');
//=> {data: {title: 'foo'}, content: 'bar', orig: '---\ntitle: foo\n---\nbar'}
Read a file and parse front matter. Returns the same object as matter().
fp {String}: file path of the file to read.options {Object}: Options to pass to gray-matter.returns: {Object}matter.read('home.md');
Stringify an object to front-matter-formatted YAML, and concatenate it to the given string.
str {String}: The content string to append to stringified front-matter.data {Object}: Front matter to stringify.options {Object}: Options to pass to js-yamlreturns: {String}matter.stringify('foo bar baz', {title: 'Home'});
Results in:
---
title: Home
---
foo bar baz
All methods exposed on the API accept an options object passed as the last argument
Type: Function
Default: undefined
Pass a custom parser on the options. This is useful if you need to, for example, define custom schemas for js-yaml.
Example
matter(str, {
parser: require('js-yaml').safeLoad
});
Type: Boolean
Default: false
Evaluate coffee-script, CSON or JavaScript in front-matter. If you aren't aware of the dangers, google is your friend.
However, if you are aware and you only use front-matter on, say, blog posts for a static site... this feature can be pretty useful.
Type: String
Default: yaml
The parser to use on the extracted front matter.
YAML is parsed by default, and the languages listed below are parsed automatically if the language is specified after the first delimiter (e.g. ---).
Valid languages are:
yamljsoncoffeecsontomljs|javascriptExample
To parse coffee front matter, you would define it as follows:
---coffee
title: 'coffee functions'
user: 'jonschlinkert'
fn:
reverse = (src) ->
src.split('').reverse().join('')
---
<%= description %>
<%= reverse(user) %>
Type: String
Default: ---
Open and close delimiters can be passed in as an array of strings.
Example:
// format delims as a string
matter.read('file.md', {delims: '~~~'});
// or an array (open/close)
matter.read('file.md', {delims: ['~~~', '~~~']});
would parse:
~~~
title: Home
~~~
This is the {{title}} page.
Given we have a page, abc.html, containing:
---
title: YAML Front matter
description: This is a page
---
<h1>{{title}}</h1>
then running the following in the command line:
matter('abc.html');
returns
{
"data": {
"title": "YAML Front matter",
"description": "This is a page"
},
"content": "<h1>{{title}}</h1>",
"original": "---\ntitle: YAML Front matter\n---\n<h1>{{title}}</h1>"
}
Blog
The following benchmarks reflect the processing time for all markdown posts in the bootstrap-blog.
front-matter.js x 271 ops/sec ±2.68% (80 runs sampled)
gray-matter.js x 4,294 ops/sec ±0.86% (91 runs sampled)
Misc
gray-matter is 12-20x faster than [front-matter] when content or front matter actually exist.
#1: complex.js
front-matter.js x 433 ops/sec ±1.21% (91 runs sampled)
gray-matter.js x 9,491 ops/sec ±1.07% (92 runs sampled)
#2: empty.js
front-matter.js x 5,744,976 ops/sec ±0.76% (99 runs sampled)
gray-matter.js x 18,048,669 ops/sec ±0.84% (93 runs sampled)
#3: matter.js
front-matter.js x 10,739 ops/sec ±2.65% (84 runs sampled)
gray-matter.js x 201,322 ops/sec ±0.71% (93 runs sampled)
#4: no-content.js
front-matter.js x 13,097 ops/sec ±3.00% (82 runs sampled)
gray-matter.js x 198,441 ops/sec ±0.49% (101 runs sampled)
#5: no-matter.js
front-matter.js x 5,420,088 ops/sec ±0.79% (96 runs sampled)
gray-matter.js x 9,559,091 ops/sec ±1.33% (92 runs sampled)
Why another YAML Front Matter library?
Because other libraries we tried failed to meet our requirements with Assemble. Some most of the libraries met most of the requirements, but none had all of them. Here are the most important:
Install dev dependencies.
npm i -d && npm test
Jon Schlinkert
Copyright (c) 2015 Jon Schlinkert
Released under the MIT license
This file was generated by verb-cli on March 10, 2015.
FAQs
Parse front-matter from a string or file. Fast, reliable and easy to use. Parses YAML front matter by default, but also has support for YAML, JSON, TOML or Coffee Front-Matter, with options to set custom delimiters. Used by metalsmith, assemble, verb and
The npm package gray-matter receives a total of 674,022 weekly downloads. As such, gray-matter popularity was classified as popular.
We found that gray-matter demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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