Refractor is a lightweight, robust, and extensible syntax highlighter that works in both Node.js and the browser. It is built on top of the Prism syntax highlighter and provides a way to highlight code syntax in various programming languages.
Syntax Highlighting
This feature allows you to highlight code syntax for a given programming language. The example highlights a simple JavaScript code snippet.
const refractor = require('refractor');
const html = refractor.highlight('const x = 42;', 'javascript');
console.log(html);Registering Languages
You can register additional languages for syntax highlighting. This example registers the Python language and highlights a Python code snippet.
const refractor = require('refractor');
const python = require('refractor/lang/python');
refractor.register(python);
const html = refractor.highlight('print("Hello, World!")', 'python');
console.log(html);Syntax Highlighting with Plugins
Refractor supports plugins to extend its functionality. This example uses the line-numbers plugin to add line numbers to the highlighted code.
const refractor = require('refractor');
const lineNumbers = require('refractor/plugins/line-numbers');
refractor.use(lineNumbers);
const html = refractor.highlight('const x = 42;', 'javascript');
console.log(html);Highlight.js is a popular syntax highlighter written in JavaScript. It automatically detects the language of the code and applies syntax highlighting. Compared to Refractor, Highlight.js is more automatic in language detection but may not be as customizable.
Prism is a lightweight, extensible syntax highlighter, built with modern web standards in mind. Refractor is built on top of Prism, so they share many similarities. However, Refractor provides a more modular approach and additional features like plugins.
CodeMirror is a versatile text editor implemented in JavaScript for the browser. It is specialized for editing code and comes with syntax highlighting capabilities. While CodeMirror is more of a full-fledged code editor, Refractor focuses solely on syntax highlighting.
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 209 languages (as of prism@1.20.0) and all
themes.
Want to use highlight.js instead?
Try lowlight!
npm:
npm install refractor
var refractor = require('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: ';' } ] } ]
Or, serialized with rehype:
var rehype = require('rehype')
var html = rehype()
.stringify({type: 'root', children: nodes})
.toString()
console.log(html)
Yields:
<span class="token string">"use strict"</span><span class="token punctuation">;</span>
Tip: Use
hast-to-hyperscriptto transform to other virtual DOMs, or DIY.
refractor.register(syntax)Register a syntax.
Needed if you’re using refractor/core.js.
var refractor = require('refractor/core.js')
var markdown = require('refractor/lang/markdown.js')
refractor.register(markdown)
console.log(refractor.highlight('*Emphasis*', 'markdown'))
Yields:
[ { type: 'element',
tagName: 'span',
properties: [Object],
children: [Array] } ]
refractor.alias(name[, alias])Register a new alias for the name language.
alias(name, alias|list)alias(aliases)name (string) — Name of a registered languagealias (string) — New alias for the registered languagelist (Array.<alias>) — List of aliasesaliases (Object.<alias|list>) — Map where each key is a name and each
value an alias or a listvar refractor = require('./core')
var markdown = require('./lang/markdown')
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.
Virtual nodes representing the highlighted value (Array.<Node>).
var refractor = require('refractor/core.js')
console.log(refractor.highlight('em { color: red }', 'css'))
Yields:
[ { type: 'element',
tagName: 'span',
properties: [Object],
children: [Array] },
{ type: 'text', value: ' ' },
// ...
{ type: 'text', value: ' red ' },
{ type: 'element',
tagName: 'span',
properties: [Object],
children: [Array] } ]
refractor.registered(language)Check if a language (name or alias) is registered.
var refractor = require('refractor/core.js')
var markdown = require('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).
Array.<string>.
var refractor = require('refractor/core.js')
var markdown = require('refractor/lang/markdown.js')
console.log(refractor.listLanguages())
refractor.register(markdown)
console.log(refractor.listLanguages())
Yields:
[ 'markup',
'xml',
'html',
'mathml',
'svg',
'css',
'clike',
'javascript',
'js' ]
[ 'markup',
'xml',
'html',
'mathml',
'svg',
'css',
'clike',
'javascript',
'js',
'markdown' ]
I do not suggest using the pre-bundled files or requiring
refractor itself in the browser as that would include a 376kb (139kb GZipped)
of code.
Instead require refractor/core.js and include only the needed syntaxes.
For example:
var refractor = require('refractor/core.js')
refractor.register(require('refractor/lang/jsx.js'))
console.log(refractor.highlight('<Dropdown primary />', 'jsx'))
Yields:
[ { type: 'element',
tagName: 'span',
properties: { className: [ 'token', 'tag' ] },
children:
[ { type: 'element',
tagName: 'span',
properties: { className: [ 'token', 'tag' ] },
children:
[ { type: 'element',
tagName: 'span',
properties: { className: [ 'token', 'punctuation' ] },
children: [ { type: 'text', value: '<' } ] },
{ type: 'text', value: 'Dropdown' } ] },
{ type: 'text', value: ' ' },
{ type: 'element',
tagName: 'span',
properties: { className: [ 'token', 'attr-name' ] },
children: [ { type: 'text', value: 'primary' } ] },
{ type: 'text', value: ' ' },
{ type: 'element',
tagName: 'span',
properties: { className: [ 'token', 'punctuation' ] },
children: [ { type: 'text', value: '/>' } ] } ] } ]
…When using browserify and minifying with tinyify this results in just 65kb of code (23kb with GZip).
refractor does not support Prism plugins:
require just what you
needAll syntaxes are included if you require('refractor').
If you’re using refractor/core.js, checked syntaxes are always included, but
unchecked syntaxes are not and must be required 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.
clikecssjavascript — alias: jsmarkup — alias: xml, html, mathml, svgabapabnfactionscriptadaantlr4 — alias: g4apacheconfaplapplescriptaqlarduinoarffasciidoc — alias: adocasm6502aspnetautohotkeyautoitbash — alias: shellbasicbatchbbcode — alias: shortcodebisonbnf — alias: rbnfbrainfuckbrightscriptbroccilclojurecmakecoffeescript — alias: coffeeconcurnas — alias: conccppcrystalcsharp — alias: dotnet, cscspcssExtrasddartdaxdiffdjango — alias: jinja2dnsZoneFiledocker — alias: dockerfileebnfeiffelejselixirelmerberlangetluaexcelFormulafactorfirestoreSecurityRulesflowfortranfsharpftlgcodegdscriptgedcomgherkingitglslgmlgographqlgroovyhamlhandlebarshaskell — alias: hshaxehclhpkphstshttpichigojamiconinform7iniiojjavajavadocjavadoclikejavastacktracejoliejqjsExtrasjsTemplatesjsdocjsonjson5jsonpjsxjuliakeymankotlinlatex — alias: tex, contextlattelesslilypondliquidlisplivescriptllvmlolcodeluamakefilemarkdown — alias: mdmarkupTemplatingmatlabmelmizarmonkeymoonscript — alias: moonn1qln4jsnand2tetrisHdlnasmneonnginxnimnixnsisobjectivecocamlopenclozparigpparserpascal — alias: objectpascalpascaligopcaxis — alias: pxperlphpExtrasphpphpdocplsqlpowerquerypowershellprocessingprologpropertiesprotobufpugpuppetpurepython — alias: pyqqmlqorerreasonregexrenpyrestriproboconfrobotframeworkruby — alias: rbrustsassassscalaschemescssshellSessionsmalltalksmartysoliditysolutionFilesoysparql — alias: rqsplunkSplsqfsqlstylusswiftt4Cst4Templatingt4Vbtaptcltextiletomltsxtt2turtletwigtypescript — alias: tsvalavbnetvelocityverilogvhdlvimvisualBasicwasmwikixeora — alias: xeoracubexojoxqueryyaml — alias: ymlziglowlight — Same, but based on highlight.jsreact-syntax-highlighter
— React component for syntax highlightingrehype-prism
— Syntax highlighting in rehypereact-refractor
— Syntax highlighter for ReactFAQs
Lightweight, robust, elegant virtual syntax highlighting using Prism
The npm package refractor receives a total of 2,238,014 weekly downloads. As such, refractor popularity was classified as popular.
We found that refractor demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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