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https://github.com/wooorm/emphasize

ANSI syntax highlighting for the terminal
https://github.com/wooorm/emphasize

ansi cli highlight syntax syntax-highlighting terminal virtual

Last synced: about 16 hours ago
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ANSI syntax highlighting for the terminal

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README 

        
# emphasize



[![Build][badge-build-image]][badge-build-url]

[![Coverage][badge-coverage-image]][badge-coverage-url]

[![Downloads][badge-downloads-image]][badge-downloads-url]

[![Size][badge-size-image]][badge-size-url]



ANSI syntax highlighting for the terminal.



## Contents



*   [What is this?](#what-is-this)

*   [When should I use this?](#when-should-i-use-this)

*   [Install](#install)

*   [Use](#use)

*   [API](#api)

    *   [`all`](#all)

    *   [`common`](#common)

    *   [`createEmphasize(grammars?)`](#createemphasizegrammars)

    *   [`emphasize.highlight(language, value[, options])`](#emphasizehighlightlanguage-value-options)

    *   [`emphasize.highlightAuto(value[, options])`](#emphasizehighlightautovalue-options)

    *   [`emphasize.listLanguages()`](#emphasizelistlanguages)

    *   [`emphasize.register(grammars)`](#emphasizeregistergrammars)

    *   [`emphasize.registerAlias(aliases)`](#emphasizeregisteraliasaliases)

    *   [`emphasize.registered(aliasOrLanguage)`](#emphasizeregisteredaliasorlanguage)

    *   [`AutoOptions`](#autooptions)

    *   [`LanguageFn`](#languagefn)

    *   [`Result`](#result)

    *   [`Sheet`](#sheet)

    *   [`Style`](#style)

*   [Compatibility](#compatibility)

*   [Security](#security)

*   [Contribute](#contribute)

*   [License](#license)



## What is this?



This package wraps [`lowlight`][github-lowlight] to output ANSI syntax

highlighting instead of HTML.

It can support 190+ programming languages.



## When should I use this?



This package is useful when you want to display code on a terminal.



## Install



This package is [ESM only][github-gist-esm].

In Node.js (version 16+),

install with [npm][npm-install]:



```sh

npm install emphasize

```



In Deno with [`esm.sh`][esm-sh]:



```js

import {all, common, createEmphasize} from 'https://esm.sh/emphasize@7'

```



In browsers with [`esm.sh`][esm-sh]:



```html



  import {all, common, createEmphasize} from 'https://esm.sh/emphasize@7?bundle'



```



## Use



Say `example.css` looks as follows:



```css

@font-face {

  font-family: Alpha;

  src: url('Bravo.otf');

}



body, .charlie, #delta {

  color: #bada55;

  background-color: rgba(33, 33, 33, 0.33);

  font-family: "Alpha", sans-serif;

}



@import url(echo.css);



@media print {

  a[href^=http]::after {

    content: attr(href)

  }

}

```



…and `example.js` contains the following:



```js

import fs from 'node:fs/promises'

import {emphasize} from 'emphasize'



const doc = String(await fs.readFile('example.css'))



const output = emphasize.highlightAuto(doc).value



console.log(output)

```



…now running `node example.js` yields:



```txt

\x1B[32m@font-face\x1B[39m {

  \x1B[33mfont-family\x1B[39m: Alpha;

  \x1B[33msrc\x1B[39m: \x1B[31murl\x1B[39m(\x1B[36m'Bravo.otf'\x1B[39m);

}



\x1B[32mbody\x1B[39m, \x1B[34m.charlie\x1B[39m, \x1B[34m#delta\x1B[39m {

  \x1B[33mcolor\x1B[39m: \x1B[36m#bada55\x1B[39m;

  \x1B[33mbackground-color\x1B[39m: \x1B[31mrgba\x1B[39m(\x1B[36m33\x1B[39m, \x1B[36m33\x1B[39m, \x1B[36m33\x1B[39m, \x1B[36m0.33\x1B[39m);

  \x1B[33mfont-family\x1B[39m: \x1B[36m"Alpha"\x1B[39m, sans-serif;

}



\x1B[32m@import\x1B[39m url(echo.css);



\x1B[32m@media\x1B[39m print {

  \x1B[32ma\x1B[39m\x1B[35m[href^=http]\x1B[39m\x1B[35m::after\x1B[39m {

    \x1B[33mcontent\x1B[39m: \x1B[31mattr\x1B[39m(href)

  }

}

```



…which looks as follows:



![Screenshot showing the code in terminal](screenshot.png)



## API



This package exports the identifiers

[`all`][api-all],

[`common`][api-common],

and [`createEmphasize`][api-create-emphasize].

There is no default export.



It exports the [TypeScript][] types

[`AutoOptions`][api-auto-options],

[`LanguageFn`][api-language-fn],

[`Result`][api-result],

[`Sheet`][api-sheet],

and [`Style`][api-style].



### `all`



Map of all (±190) grammars ([`Record`][api-language-fn]).



See [`all` from `lowlight`][github-lowlight-all].



### `common`



Map of common (37) grammars ([`Record`][api-language-fn]).



See [`common` from `lowlight`][github-lowlight-common].



### `createEmphasize(grammars?)`



Create a `emphasize` instance.



###### Parameters



*   `grammars` ([`Record`][api-language-fn], optional)

    — grammars to add



###### Returns



Emphasize (`emphasize`).



### `emphasize.highlight(language, value[, options])`



Highlight `value` (code) as `language` (name).



###### Parameters



*   `language` (`string`)

    — programming language [name][github-highlight-names]

*   `value` (`string`)

    — code to highlight

*   `sheet` ([`Sheet`][api-sheet], optional)

    — style sheet



###### Returns



[`Result`][api-result].



### `emphasize.highlightAuto(value[, options])`



Highlight `value` (code) and guess its programming language.



###### Parameters



*   `value` (`string`)

    — code to highlight

*   `options` ([`AutoOptions`][api-auto-options] or [`Sheet`][api-sheet],

    optional)

    — configuration or style sheet



###### Returns



[`Result`][api-result].



### `emphasize.listLanguages()`



List registered languages.



See [`lowlight.listLanguages`][github-lowlight-list-languages].



### `emphasize.register(grammars)`



Register languages.



See [`lowlight.register`][github-lowlight-register].



### `emphasize.registerAlias(aliases)`



Register aliases.



See [`lowlight.registerAlias`][github-lowlight-register-alias].



### `emphasize.registered(aliasOrLanguage)`



Check whether an alias or name is registered.



See [`lowlight.registered`][github-lowlight-registered].



### `AutoOptions`



Configuration for `highlightAuto` (TypeScript type).



###### Fields



*   `sheet` ([`Sheet`][api-sheet], optional)

    — sheet

*   `subset` (`Array`, default: all registered languages)

    — list of allowed languages



### `LanguageFn`



Highlight.js grammar (TypeScript type).



See [`LanguageFn` from `lowlight`][github-lowlight-langauge-fn].



### `Result`



Result (TypeScript type).



###### Fields



*   `language` (`string` or `undefined`)

    — detected programming language.

*   `relevance` (`number` or `undefined`)

    — how sure `lowlight` is that the given code is in the language

*   `value` (`string`)

    — highlighted code



### `Sheet`



Map [`highlight.js` classes][github-highlight-classes] to styles functions

(TypeScript type).



The `hljs-` prefix must not be used in those classes.

The “descendant selector” (a space) is supported.



For convenience [chalk’s chaining of styles][github-chalk-styles] is suggested.

An abbreviated example is as follows:



```js

{

  'comment': chalk.gray,

  'meta meta-string': chalk.cyan,

  'meta keyword': chalk.magenta,

  'emphasis': chalk.italic,

  'strong': chalk.bold,

  'formula': chalk.inverse

}

```



###### Type



```ts

type Sheet = Record

```



### `Style`



Color something (TypeScript type).



###### Parameters



*   `value` (`string`)

    — input



###### Returns



Output (`string`).



## Compatibility



This projects is compatible with maintained versions of Node.js.



When we cut a new major release,

we drop support for unmaintained versions of Node.

This means we try to keep the current release line,

`emphasize@7`,

compatible with Node.js 16.



## Security



This package is safe.



## Contribute



Yes please!

See [How to Contribute to Open Source][open-source-guide-contribute].



## License



[MIT][file-license] © [Titus Wormer][wooorm]



[api-all]: #all



[api-auto-options]: #autooptions



[api-common]: #common



[api-create-emphasize]: #createemphasizegrammars



[api-language-fn]: #languagefn



[api-result]: #result



[api-sheet]: #sheet



[api-style]: #style



[badge-build-image]: https://github.com/wooorm/emphasize/workflows/main/badge.svg



[badge-build-url]: https://github.com/wooorm/emphasize/actions



[badge-coverage-image]: https://img.shields.io/codecov/c/github/wooorm/emphasize.svg



[badge-coverage-url]: https://codecov.io/github/wooorm/emphasize



[badge-downloads-image]: https://img.shields.io/npm/dm/emphasize.svg



[badge-downloads-url]: https://www.npmjs.com/package/emphasize



[badge-size-image]: https://img.shields.io/bundlejs/size/emphasize



[badge-size-url]: https://bundlejs.com/?q=emphasize



[npm-install]: https://docs.npmjs.com/cli/install



[esm-sh]: https://esm.sh



[file-license]: license



[github-chalk-styles]: https://github.com/chalk/chalk#styles



[github-gist-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c



[github-highlight-classes]: https://highlightjs.readthedocs.io/en/latest/css-classes-reference.html



[github-highlight-names]: https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md



[github-lowlight]: https://github.com/wooorm/lowlight



[github-lowlight-all]: https://github.com/wooorm/lowlight#all



[github-lowlight-common]: https://github.com/wooorm/lowlight#common



[github-lowlight-langauge-fn]: https://github.com/wooorm/lowlight#languagefn



[github-lowlight-list-languages]: https://github.com/wooorm/lowlight#lowlightlistlanguages



[github-lowlight-register]: https://github.com/wooorm/lowlight#lowlightregistergrammars



[github-lowlight-register-alias]: https://github.com/wooorm/lowlight#lowlightregisteraliasaliases



[github-lowlight-registered]: https://github.com/wooorm/lowlight#lowlightregisteredaliasorlanguage



[open-source-guide-contribute]: https://opensource.guide/how-to-contribute/



[typescript]: https://www.typescriptlang.org



[wooorm]: https://wooorm.com