Codemirror

The excellent CodeMirror editor as a React.js component.

Demo & Examples

Live demo: JedWatson.github.io/react-codemirror

To build the examples locally, run:

npm install
npm start

Then open localhost:8000 in a browser.

Installation

The easiest way to use codemirror is to install it from NPM and include it in your own React build process (using Browserify, Webpack, etc).

You can also use the standalone build by including dist/react-codemirror.js in your page. If you use this, make sure you have already included React, and it is available as a global variable.

npm install react-codemirror --save

Usage

Require the CodeMirror component and render it with JSX:

var React = require('react');
var CodeMirror = require('react-codemirror');

var App = React.createClass({
	getInitialState: function() {
		return {
			code: "// Code",
		};
	},
	updateCode: function(newCode) {
		this.setState({
			code: newCode,
		});
	},
	render: function() {
		var options = {
			lineNumbers: true,
		};
		return <CodeMirror value={this.state.code} onChange={this.updateCode} options={options} />
	}
});

React.render(<App />, document.getElementById('app'));

Include the CSS

Ensure that CodeMirror's stylesheet codemirror.css is loaded.

If you're using LESS (similar for Sass) you can import the css directly from the codemirror package, as shown in example.less:

@import (inline) "./node_modules/codemirror/lib/codemirror.css";

If you're using Webpack with the css loader, you can require the codemirror css in your application instead:

require('codemirror/lib/codemirror.css');

Alternatively, you can explicitly link the codemirror.css file from the CodeMirror project in your index.html file, e.g <link href="css/codemirror.css" rel="stylesheet">.

Methods

• focus focuses the CodeMirror instance
• getCodeMirror returns the CodeMirror instance, available .

You can interact with the CodeMirror instance using a ref and the getCodeMirror() method after the componentDidMount lifecycle event has fired (including inside the componentDidMount event in a parent Component).

Properties

• autoFocus Boolean automatically focuses the editor when it is mounted (default false)
• autoSave Boolean automatically persist changes to underlying textarea (default false)
• className String adds a custom css class to the editor
• codeMirrorInstance Function provides a specific CodeMirror instance (defaults to require('codemirror'))
• defaultValue String provides a default (not change tracked) value to the editor
• name String sets the name of the editor input field
• options Object options passed to the CodeMirror instance
• onChange Function (newValue) called when a change is made
• onCursorActivity Function (codemirror) called when the cursor is moved
• onFocusChange Function (focused) called when the editor is focused or loses focus
• onScroll Function (scrollInfo) called when the editor is scrolled
• preserveScrollPosition Boolean=false preserve previous scroll position after updating value
• value String the editor value

See the CodeMirror API Docs for the available options.

Using Language Modes

Several language modes are included with CodeMirror for syntax highlighting.

By default (to optimise bundle size) all modes are not included. To enable syntax highlighting:

• install the codemirror package dependency (in addition to react-codemirror)
• require the language modes you wish to make available after you require react-codemirror itself
• set the mode option in the options object

var React = require('react');
var CodeMirror = require('react-codemirror');
require('codemirror/mode/javascript/javascript');
require('codemirror/mode/xml/xml');
require('codemirror/mode/markdown/markdown');

<CodeMirror ... options={{
	mode: 'javascript',
}} />

See the example source for a reference implementation including JavaScript and markdown syntax highlighting.

License

Copyright (c) 2016 Jed Watson. MIT Licensed.