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sj26 / refractor

Lightweight, robust, elegant virtual syntax highlighting using Prism

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refractor

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Lightweight, robust, elegant virtual syntax highlighting using Prism. Useful for virtual DOMs and non-HTML things. Perfect for React, VDOM, and others.

refractor is built to work with all syntaxes supported by Prism, that’s 237 languages (as of prism@1.23.0) and all themes.

Want to use highlight.js instead? Try lowlight!

Contents

Install

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

npm:

npm install refractor

Use in the browser »

Use

import {refractor} from 'refractor'

var nodes = refractor.highlight('"use strict";', 'js')

console.log(nodes)

Yields:

[
  {
    type: 'element',
    tagName: 'span',
    properties: {className: ['token', 'string']},
    children: [{type: 'text', value: '"use strict"'}]
  },
  {
    type: 'element',
    tagName: 'span',
    properties: {className: ['token', 'punctuation']},
    children: [{type: 'text', value: ';'}]
  }
]

Which serialized with rehype or hast-util-to-html yields (you may have to wrap it into a fragment like so: {type: 'root', children: nodes}):

<span class="token string">"use strict"</span><span class="token punctuation">;</span>

Tip: Use hast-to-hyperscript to transform to other virtual DOMs, or DIY.

API

This package exports the following identifiers: refractor. There is no default export.

refractor.register(syntax)

Register a syntax. Needed if you’re using refractor/core.

Example
import {refractor} from 'refractor/core.js'
import markdown from 'refractor/lang/markdown.js'

refractor.register(markdown)

console.log(refractor.highlight('*Emphasis*', 'markdown'))

Yields:

[
  {
    type: 'element',
    tagName: 'span',
    properties: {className: [Array]},
    children: [[Object], [Object], [Object]]
  }
]

refractor.alias(name[, alias])

Register a new alias for the name language.

Signatures
  • alias(name, alias|list)
  • alias(aliases)
Parameters
  • name (string) — Name of a registered language
  • alias (string) — New alias for the registered language
  • list (Array.<alias>) — List of aliases
  • aliases (Object.<alias|list>) — Map where each key is a name and each value an alias or a list
Example
import {refractor} from 'refractor/core.js'
import markdown from 'refractor/lang/markdown.js'

refractor.register(markdown)

// refractor.highlight('*Emphasis*', 'mdown')
// ^ would throw: Error: Unknown language: `mdown` is not registered

refractor.alias({markdown: ['mdown', 'mkdn', 'mdwn', 'ron']})
refractor.highlight('*Emphasis*', 'mdown')
// ^ Works!

refractor.highlight(value, language)

Parse value (string) according to the language (name or alias) syntax.

Returns

Virtual nodes representing the highlighted value (Array.<Node>).

Example
import {refractor} from 'refractor/core.js'

console.log(refractor.highlight('em { color: red }', 'css'))

Yields:

[
  {
    type: 'element',
    tagName: 'span',
    properties: {className: [Array]},
    children: [[Object]]
  },
  {type: 'text', value: ' '},
  // …
  {type: 'text', value: ' red '},
  {
    type: 'element',
    tagName: 'span',
    properties: {className: [Array]},
    children: [[Object]]
  }
]

refractor.registered(language)

Check if a language (name or alias) is registered.

Example
import {refractor} from 'refractor/core.js'
import {markdown} from 'refractor/lang/markdown.js'

console.log(refractor.registered('markdown'))

refractor.register(markdown)

console.log(refractor.registered('markdown'))

Yields:

false
true

refractor.listLanguages()

List all registered languages (names and aliases).

Returns

Array.<string>.

Example
import {refractor} from 'refractor/core.js'
import {markdown} from 'refractor/lang/markdown.js'

console.log(refractor.listLanguages())

refractor.register(markdown)

console.log(refractor.listLanguages())

Yields:

[
  'markup',
  'html',
  // …
  'javascript',
  'js'
]
[
  'markup',
  'html',
  // …
  'javascript',
  'js',
  'markdown',
  'md'
]

Browser

It is not suggested to import refractor itself in the browser as that would include a 500kb (187kb minzipped) of code.

Instead import refractor/core.js and include only the needed syntaxes. For example:

import {refractor} from 'refractor/core.js'
import jsx from 'refractor/lang/jsx.js'

refractor.register(jsx)

console.log(refractor.highlight('<Dropdown primary />', 'jsx'))

…when using esbuild this results in 35.8kB of code (14kb minzipped).

Plugins

refractor does not support Prism plugins:

  1. Prism plugins often deal with the DOM, not Prism tokens
  2. Prism is made using global variables instead of a module format, so all syntaxes below are custom built to work so you can import just what you need

Syntaxes

All syntaxes are included if you import 'refractor'. If you’re using refractor/core.js, checked syntaxes are always included, but unchecked syntaxes are not and must be imported and registered.

Unlike in Prism, cssExtras and phpExtras are camel-cased instead of dash-cased.

Only these custom built syntaxes will work with refractor because Prism’s own syntaxes are made to work with global variables and are not requirable.

Related

Projects

License

MIT © Titus Wormer

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Lightweight, robust, elegant virtual syntax highlighting using Prism

License:MIT License

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Language:JavaScript 100.0%