prismjs-terminal

PrismJS, but for terminal output.

USAGE

// ESM only, sorry, blame chalk
// But less reason to use CommonJS for new CLI apps anyway
import { highlight } from 'prismjs-terminal'

// get some code somehow
import { readFileSync } from 'fs'
const code = readFileSync('some-file.ts', 'utf8')

// highlight it
console.log(highlight(code, 'typescript'))

Custom Themes

Instead of CSS, themes are defined using an object with styling functions that take a string and return a string.

The _ style rule applies to the block as a whole, and is used as the default style. This is where you'd usually port a PrismJS theme's code[class*="language-"] css rule.

The lineNumber style rule will apply to line numbers, if they are used.

The semantics are similar to CSS, where a nested property will be applied to nodes within that nesting stack with a higher priority the more tags that match, and later rules taking precedence over earlier ones. It's not a full CSS selector syntax though, so things like .token.italic.bold aren't supported. Just individual token class names, possibly nested. Also, chalk is not CSS, and a terminal is not a browser, so there are some differences and limitations of course.

Aliases are also not supported, styles have to be applied to the actual parsed class names PrismJS provides.

For example:

import { defaultTheme, Theme } from 'prismjs-terminal'
import chalk from 'chalk'
const theme: Theme = {
  // any (s:string)=>string function is allowed
  comment: chalk.hex('#d75fff').italic,

  // can provide multiple functions, which is useful if they
  // aren't chainable chalk methods
  function: [chalk.hex('#f08'), s => ` >${s}< `],

  // nest by separating with a space
  // will turn `/abc/gm` into:
  // chalk.bold('/' + chalk.green('abc') + '/' + chalk.blue('gm'))
  regex: chalk.bold,
  'regex regex-source': chalk.green,
  'regex regex-flags': chalk.blue,

  // apply one style to multiple token names by separating with `,`
  'string, number': chalk.green,

  // See the defaultTheme export for more examples.
}
console.log(highlight(code, 'typescript', { theme }))

// can also use one of the included ones
console.log(highlight(code, 'typescript', { theme: 'xonokai' }))

See the themes directory in this repo for more examples.

API

• interface PrismJSTerminalOpts

  • theme The theme to use. Either a Theme object, or a string identifying one of the built-in themes. Defaults to 'moria'.
  • language The language of the supplied code to highlight. Defaults to tsx if no filename is provided, or else tries to infer the language from the filename. You must have previously called loadLanguages([...]) from PrismJS in order to highlight a given language, if you want something that is not automatically included when tsx and typescript are included.
  • minWidth The minimum width to make the block on the screen. Defaults to 0.
  • maxWidth The maximum width to make the block on the screen. Defaults to process.stdout.columns or 80.
  • padding How many spaces to horizontally pad the code block. Defaults to 1.
  • lineNumbers Whether or not to prepend a line number to each line. Defaults to false.

• highlight(code: string, opts?: PrismJSTerminalOpts): string

  Highlight the string of code provided, returning the string of highlighted code.

• highlightFile(filename: string, opts?: PrismJSTerminalOpts): Promise<string>

  Read the filename provided, and highlight its code. If a language is not provided in the opts, it will attempt to infer from the filename.

• highlightFileSync(filename: string, opts?: PrismJSTerminalOpts): string

  Synchronous highlightFile.

• Themes:

  More are welcome! If you have a PrismJS theme you like, do send a PR. Of course not everything translates, but it's quite straightforward to take a PrismJS CSS file and turn all the color: #... lines into chalk.hex('#...') calls.

  Theme objects can be either a Map or object where the keys are the selectors and the values are either a styling function or an array of styling functions to be applied in order.

  • debug This just dumps the code wrapped in <tag>...</tag> to see what the token names are. Useful for tests and such.
  • plain No styling, just the code as plain text.
  • github Port of GHColors prismjs theme.
  • moria Inspired by Vim Moria color scheme.
  • prismDark Port of the prism-dark PrismJS theme.
  • xonokai Port of the xonokai PrismJS theme.