@codemirror/language

@codemirror/language

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This package implements the language support infrastructure for the CodeMirror code editor.

The project page has more information, a number of examples and the documentation.

This code is released under an MIT license.

We aim to be an inclusive, welcoming community. To make that explicit, we have a code of conduct that applies to communication around the project.

Usage

Setting up a language from a Lezer parser looks like this:

import {parser} from "@lezer/json"
import {LRLanguage, continuedIndent, indentNodeProp,
        foldNodeProp, foldInside} from "@codemirror/language"

export const jsonLanguage = LRLanguage.define({
  name: "json",
  parser: parser.configure({
    props: [
      indentNodeProp.add({
        Object: continuedIndent({except: /^\s*\}/}),
        Array: continuedIndent({except: /^\s*\]/})
      }),
      foldNodeProp.add({
        "Object Array": foldInside
      })
    ]
  }),
  languageData: {
    closeBrackets: {brackets: ["[", "{", '"']},
    indentOnInput: /^\s*[\}\]]$/
  }
})

Often, you'll also use this package just to access some specific language-related features, such as accessing the editor's syntax tree...

import {syntaxTree} from "@codemirror/language"

const tree = syntaxTree(view)

... or computing the appriate indentation at a given point.

import {getIndentation} from "@codemirror/language"

console.log(getIndentation(view.state, view.state.selection.main.head))

Changelog

6.11.3 (2025-08-15)

Bug fixes

Make the stream parser user 4 times smaller chunks to reduce the amount of re-parsed code on changes.

Similar packages

Other packages similar to @codemirror/language

monaco-editor

The Monaco Editor is the code editor that powers VS Code, offering rich language support and development features. Compared to @codemirror/language, Monaco provides a more extensive set of features out of the box, including integrated syntax highlighting, autocompletion, and debugging for a wide range of languages. However, it might be heavier and more complex to integrate into web projects.

ace-builds

Ace is another popular code editor library that can be embedded in web pages and applications. Similar to @codemirror/language, it offers syntax highlighting, autocompletion, and other editing features for various programming languages. Ace is known for its extensibility and customizability, though it might not be as modern or as actively developed as CodeMirror.