codemirror

What is codemirror?

CodeMirror is a versatile text editor implemented in JavaScript for the browser. It is specialized for editing code and comes with a number of language modes and addons that implement more advanced editing functionality. A rich programming API and a CSS theming system are available for customizing CodeMirror to fit the needs of the project.

What are codemirror's main functionalities?

Syntax highlighting

This feature allows for syntax highlighting of code written in various programming languages. The example code initializes a CodeMirror instance with JavaScript syntax highlighting.

var editor = CodeMirror.fromTextArea(document.getElementById('code'), {mode: 'javascript'});

Code editing

CodeMirror provides a rich text editor for code, with features like auto-indentation, line numbers, and bracket matching. The example code creates an editor instance with some JavaScript code pre-filled.

var editor = CodeMirror(document.body, {value: 'function myScript(){return 100;}', mode: 'javascript'});

Autocompletion

Autocompletion can be enabled to suggest completions for the current token. The example code sets up an event listener to trigger autocompletion on certain inputs.

editor.on('inputRead', function onChange(editor, input) { if (input.text[0] === ';' || input.text[0] === ' ') { return; } CodeMirror.commands.autocomplete(editor); });

Themes

CodeMirror supports various themes to customize the appearance of the editor. The example code initializes a CodeMirror instance with the Monokai theme.

var editor = CodeMirror.fromTextArea(document.getElementById('code'), {mode: 'javascript', theme: 'monokai'});

Addons

CodeMirror has a variety of addons that can extend its functionality, such as displaying line numbers or matching brackets. The example code enables line numbers and bracket matching for the editor.

var editor = CodeMirror.fromTextArea(document.getElementById('code'), {mode: 'javascript', lineNumbers: true, matchBrackets: true});

Other packages similar to codemirror

ace

Ace is a standalone code editor written in JavaScript. It matches many of the features of CodeMirror, such as syntax highlighting, themes, and extensions. However, Ace is known for its performance and is used in large-scale applications like Cloud9 IDE.

monaco-editor

Monaco Editor is the code editor that powers VS Code, which is known for its rich IntelliSense, integrated debugging, and embedded Git control. It's more feature-rich compared to CodeMirror and is designed to work well in any browser.

brace

Brace is a fork of Ace that is browserify compatible. It has a similar feature set to Ace and by extension, CodeMirror, but it is designed to be easier to install and use with browserify.

README

codemirror

[ WEBSITE | DOCS | ISSUES | FORUM | CHANGELOG ]

This package provides an example configuration for the CodeMirror code editor. The actual editor is implemented in the various packages under the @codemirror scope, which this package depends on.

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

import {EditorView, basicSetup} from "codemirror"

const view = new EditorView({
  parent: document.body,
  doc: "Hello",
  extensions: [basicSetup /* ... */]
})

This sets up a basic code editor containing the word "Hello". You'll usually want to add at least a language mode to your configuration.

Changelog

6.0.2 (2025-06-19)

Bug fixes

Make sure to include a .d.cts file to make TypeScript happy.