react-codemirror is a free, open source ides & code editors project written in TypeScript and released under MIT. It has 2,258 GitHub stars, 162 forks and 172 open issues, and was last pushed 20 days ago. On this registry it ranks #39 of 43 tracked projects in IDEs & Code Editors, with 5 head-to-head comparisons available.

What is react-codemirror?

react-codemirror is the npm package @uiw/react-codemirror: a CodeMirror 6 editor component for React, written in TypeScript, intended for React developers who need a code editor embedded inside an application rather than a standalone editing tool.

What it is

This project is a React binding around CodeMirror 6, distributed on npm as @uiw/react-codemirror. The codebase is TypeScript and licensed MIT, and the repository also publishes companion packages: react-codemirror-merge, @uiw/codemirror-extensions-basic-setup, and @uiw/codemirror-extensions-color. Versions after @uiw/react-codemirror@v4 target CodeMirror 6, while earlier versions targeted the older CodeMirror line. The README states explicitly that the package is not dependent on uiw, so the component can be adopted without pulling in that wider toolkit.

The concrete problem it solves is the impedance mismatch between CodeMirror 6 and React. CodeMirror 6 is built around an editor view, extensions, and its own state model, which do not map cleanly onto React's component lifecycle and re-render behaviour. This package wraps that surface in a React component with hooks, so state changes flow through props instead of manual imperative wiring. It occupies the slot held by the older react-codemirror2 binding, which the topic list still carries; that package served CodeMirror 5 users, and this one is the CodeMirror 6 counterpart in the same React editor niche.

Key capabilities

  • @uiw/react-codemirror component built on CodeMirror 6 for all versions after v4.
  • React Hook support, requiring React 16.8 or newer.
  • Written in TypeScript, which the README lists as the basis for its code hints.
  • A bundled build that can be used directly in the browser, without a build pipeline.
  • Theme customisation, with a theme editor and worked examples such as a Dracula theme.
  • Companion packages for adjacent work: react-codemirror-merge for merge and diff views, plus @uiw/codemirror-extensions-basic-setup and @uiw/codemirror-extensions-color.
  • A SwiftUI wrapper for CodeMirror 6, published separately as jaywcjlove/swiftui-codemirror.

Who uses it and how

  • React application teams embedding an in-app code editor, configuration pane, or script input field inside an existing product surface.
  • Projects on React 16.8 or later that want the editor driven by hooks rather than class lifecycle methods.
  • Browser-only and prototype setups that use the bundled build directly in the page, with no bundler step.
  • Teams that need side-by-side or merge views, using react-codemirror-merge alongside the core component.
  • Theme authors and design-focused teams, using the theme editor to produce custom CodeMirror 6 themes and previewing them against examples such as Dracula.

Getting started

Install with npm install @uiw/react-codemirror --save; the README notes the package is not dependent on uiw. Live samples and the theme editor are published at https://uiwjs.github.io/react-codemirror/.

How it compares

No list of paid products that this project replaces is provided in the available facts. Among the tools the facts do name, it sits as the React binding for CodeMirror 6 rather than a replacement for it, next to the older react-codemirror2 binding that still appears in its discovery topics, and it stands beside the author's separate SwiftUI wrapper for the same CodeMirror 6 core.

When to use it — and when not to

Nothing has to be operated server-side: this is a client-side React package, so there is no database, object storage, or SMTP service to run, and adoption cost is an npm dependency plus a bundler. Teams not on React, or those who only need the raw editor, should use CodeMirror 6 directly instead of going through a wrapper. The honest caveats are the project's size and churn: 172 open issues against 2258 stars, a README that is largely promotional badges and a short feature list, and a primary demo site that carries much of the documentation burden.

project readme (upstream, from github) — read inline

Special thanks to:

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react-codemirror logo

react-codemirror

Buy me a coffee Follow On X NPM Downloads Build & Deploy Open in unpkg npm version Coverage Status Open in Gitpod

CodeMirror component for React. Demo Preview: @uiwjs.github.io/react-codemirror

Features:

🚀 Quickly and easily configure the API.
🌱 Versions after @uiw/react-codemirror@v4 use codemirror 6. #88.
⚛️ Support the features of React Hook(requires React 16.8+).
📚 Use Typescript to write, better code hints.
🌐 The bundled version supports use directly in the browser #267.
🌎 There are better sample previews.
🎨 Support theme customization, provide theme editor.
🧑‍💻 SwiftUI wrapper for CodeMirror 6.

Install

Not dependent on uiw.

npm install @uiw/react-codemirror --save

All Packages

Usage

Open in CodeSandbox

import React from 'react';
import CodeMirror from '@uiw/react-codemirror';
import { javascript } from '@codemirror/lang-javascript';

function App() {
  const [value, setValue] = React.useState("console.log('hello world!');");
  const onChange = React.useCallback((val, viewUpdate) => {
    console.log('val:', val);
    setValue(val);
  }, []);
  return <CodeMirror value={value} height="200px" extensions={[javascript({ jsx: true })]} onChange={onChange} />;
}
export default App;

Support Language

Open in CodeSandbox

import CodeMirror from '@uiw/react-codemirror';
import { StreamLanguage } from '@codemirror/language';
import { go } from '@codemirror/legacy-modes/mode/go';

const goLang = `package main
import "fmt"

func main() {
  fmt.Println("Hello, 世界")
}`;

export default function App() {
  return <CodeMirror value={goLang} height="200px" extensions={[StreamLanguage.define(go)]} />;
}

Markdown Example

Markdown language code is automatically highlighted.

Open in CodeSandbox

import CodeMirror from '@uiw/react-codemirror';
import { markdown, markdownLanguage } from '@codemirror/lang-markdown';
import { languages } from '@codemirror/language-data';

const code = `## Title

\`\`\`jsx
function Demo() {
  return <div>demo</div>
}
\`\`\`

\`\`\`bash
# Not dependent on uiw.
npm install @codemirror/lang-markdown --save
npm install @codemirror/language-data --save
\`\`\`

[weisit ulr](https://uiwjs.github.io/react-codemirror/)

\`\`\`go
package main
import "fmt"
func main() {
  fmt.Println("Hello, 世界")
}
\`\`\`
`;

export default function App() {
  return <CodeMirror value={code} extensions={[markdown({ base: markdownLanguage, codeLanguages: languages })]} />;
}

Codemirror Merge

A component that highlights the changes between two versions of a file in a side-by-side view, highlighting added, modified, or deleted lines of code.

npm install react-codemirror-merge  --save
import CodeMirrorMerge from 'react-codemirror-merge';
import { EditorView } from 'codemirror';
import { EditorState } from '@codemirror/state';

const Original = CodeMirrorMerge.Original;
const Modified = CodeMirrorMerge.Modified;
let doc = `one
two
three
four
five`;

export const Example = () => {
  return (
    <CodeMirrorMerge>
      <Original value={doc} />
      <Modified
        value={doc.replace(/t/g, 'T') + 'Six'}
        extensions={[EditorView.editable.of(false), EditorState.readOnly.of(true)]}
      />
    </CodeMirrorMerge>
  );
};

Support Hook

Open in CodeSandbox

import { useEffect, useMemo, useRef } from 'react';
import { useCodeMirror } from '@uiw/react-codemirror';
import { javascript } from '@codemirror/lang-javascript';

const code = "console.log('hello world!');\n\n\n";
// Define the extensions outside the component for the best performance.
// If you need dynamic extensions, use React.useMemo to minimize reference changes
// which cause costly re-renders.
const extensions = [javascript()];

export default function App() {
  const editor = useRef();
  const { setContainer } = useCodeMirror({
    container: editor.current,
    extensions,
    value: code,
  });

  useEffect(() => {
    if (editor.current) {
      setContainer(editor.current);
    }
  }, [editor.current]);

  return <div ref={editor} />;
}

Using Theme

We have created a theme editor where you can define your own theme. We have also defined some themes ourselves, which can be installed and used directly. Below is a usage example:

import CodeMirror from '@uiw/react-codemirror';
import { javascript } from '@codemirror/lang-javascript';
import { okaidia } from '@uiw/codemirror-theme-okaidia';

const extensions = [javascript({ jsx: true })];

export default function App() {
  return <CodeMirror value="console.log('hello world!');" height="200px" theme={okaidia} extensions={extensions} />;
}

Using custom theme

import CodeMirror from '@uiw/react-codemirror';
import { createTheme } from '@uiw/codemirror-themes';
import { javascript } from '@codemirror/lang-javascript';
import { tags as t } from '@lezer/highlight';

const myTheme = createTheme({
  theme: 'light',
  settings: {
    background: '#ffffff',
    backgroundImage: '',
    foreground: '#75baff',
    caret: '#5d00ff',
    selection: '#036dd626',
    selectionMatch: '#036dd626',
    lineHighlight: '#8a91991a',
    gutterBackground: '#fff',
    gutterForeground: '#8a919966',
  },
  styles: [
    { tag: t.comment, color: '#787b8099' },
    { tag: t.variableName, color: '#0080ff' },
    { tag: [t.string, t.special(t.brace)], color: '#5c6166' },
    { tag: t.number, color: '#5c6166' },
    { tag: t.bool, color: '#5c6166' },
    { tag: t.null, color: '#5c6166' },
    { tag: t.keyword, color: '#5c6166' },
    { tag: t.operator, color: '#5c6166' },
    { tag: t.className, color: '#5c6166' },
    { tag: t.definition(t.typeName), color: '#5c6166' },
    { tag: t.typeName, color: '#5c6166' },
    { tag: t.angleBracket, color: '#5c6166' },
    { tag: t.tagName, color: '#5c6166' },
    { tag: t.attributeName, color: '#5c6166' },
  ],
});
const extensions = [javascript({ jsx: true })];

export default function App() {
  const onChange = React.useCallback((value, viewUpdate) => {
    console.log('value:', value);
  }, []);
  return (
    <CodeMirror
      value="console.log('hello world!');"
      height="200px"
      theme={myTheme}
      extensions={extensions}
      onChange={onChange}
    />
  );
}

Use initialState to restore state from JSON-serialized representation

CodeMirror allows to serialize editor state to JSON representation with toJSON function for persistency or other needs. This JSON representation can be later used to recreate ReactCodeMirror component with the same internal state.

For example, this is how undo history can be saved in the local storage, so that it remains after the page reloads

import CodeMirror from '@uiw/react-codemirror';
import { historyField } from '@codemirror/commands';

// When custom fields should be serialized, you can pass them in as an object mapping property names to fields.
// See [toJSON](https://codemirror.net/docs/ref/#state.EditorState.toJSON) documentation for more details
const stateFields = { history: historyField };

export function EditorWithInitialState() {
  const serializedState = localStorage.getItem('myEditorState');
  const value = localStorage.getItem('myValue') || '';

  return (
    <CodeMirror
      value={value}
      initialState={
        serializedState
          ? {
              json: JSON.parse(serializedState || ''),
              fields: stateFields,
            }
          : undefined
      }
      onChange={(value, viewUpdate) => {
        localStorage.setItem('myValue', value);

        const state = viewUpdate.state.toJSON(stateFields);
        localStorage.setItem('myEditorState', JSON.stringify(state));
      }}
    />
  );
}

Props

  • value?: string value of the auto created model in the editor.
  • width?: string width of editor. Defaults to auto.
  • height?: string height of editor. Defaults to auto.
  • theme?: 'light' / 'dark' / Extension Defaults to 'light'.
import React from 'react';
import { EditorState, EditorStateConfig, Extension } from '@codemirror/state';
import { EditorView, ViewUpdate } from '@codemirror/view';
export * from '@codemirror/view';
export * from '@codemirror/basic-setup';
export * from '@codemirror/state';
export declare const ExternalChange: import('@codemirror/state').AnnotationType<boolean>;
export interface UseCodeMirror extends ReactCodeMirrorProps {
  container?: HTMLDivElement | null;
}
export declare function useCodeMirror(props: UseCodeMirror): {
  state: EditorState | undefined;
  setState: import('react').Dispatch<import('react').SetStateAction<EditorState | undefined>>;
  view: EditorView | undefined;
  setView: import('react').Dispatch<import('react').SetStateAction<EditorView | undefined>>;
  container: HTMLDivElement | null | undefined;
  setContainer: import('react').Dispatch<import('react').SetStateAction<HTMLDivElement | null | undefined>>;
};
export interface ReactCodeMirrorProps
  extends
    Omit<EditorStateConfig, 'doc' | 'extensions'>,
    Omit<React.HTMLAttributes<HTMLDivElement>, 'onChange' | 'placeholder'> {
  /** value of the auto created model in the editor. */
  value?: string;
  height?: string;
  minHeight?: string;
  maxHeight?: string;
  width?: string;
  minWidth?: string;
  maxWidth?: string;
  /** focus on the editor. */
  autoFocus?: boolean;
  /** Enables a placeholder—a piece of example content to show when the editor is empty. */
  placeholder?: string | HTMLElement;
  /**
   * `light` / `dark` / `Extension` Defaults to `light`.
   * @default light
   */
  theme?: 'light' | 'dark' | Extension;
  /**
   * Whether to optional basicSetup by default
   * @default true
   */
  basicSetup?: boolean | BasicSetupOptions;
  /**
   * This disables editing of the editor content by the user.
   * @default true
   */
  editable?: boolean;
  /**
   * This disables editing of the editor content by the user.
   * @default false
   */
  readOnly?: boolean;
  /**
   * Controls whether pressing the `Tab` key inserts a tab character and indents the text (`true`)
   * or behaves according to the browser's default behavior (`false`).
   * @default true
   */
  indentWithTab?: boolean;
  /** Fired whenever a change occurs to the document. */
  onChange?(value: string, viewUpdate: ViewUpdate): void;
  /** Some data on the statistics editor. */
  onStatistics?(data: Statistics): void;
  /** The first time the editor executes the event. */
  onCreateEditor?(view: EditorView, state: EditorState): void;
  /** Fired whenever any state change occurs within the editor, including non-document changes like lint results. */
  onUpdate?(viewUpdate: ViewUpdate): void;
  /**
   * Extension values can be [provided](https://codemirror.net/6/docs/ref/#state.EditorStateConfig.extensions) when creating a state to attach various kinds of configuration and behavior information.
   * They can either be built-in extension-providing objects,
   * such as [state fields](https://codemirror.net/6/docs/ref/#state.StateField) or [facet providers](https://codemirror.net/6/docs/ref/#state.Facet.of),
   * or objects with an extension in its `extension` property. Extensions can be nested in arrays arbitrarily deep—they will be flattened when processed.
   */
  extensions?: Extension[];
  /**
   * If the view is going to be mounted in a shadow root or document other than the one held by the global variable document (the default), you should pass it here.
   * Originally from the [config of EditorView](https://codemirror.net/6/docs/ref/#view.EditorView.constructor%5Econfig.root)
   */
  root?: ShadowRoot | Document;
  /**
   * Create a state from its JSON representation serialized with [toJSON](https://codemirror.net/docs/ref/#state.EditorState.toJSON) function
   */
  initialState?: {
    json: any;
    fields?: Record<'string', StateField<any>>;
  };
}
export interface ReactCodeMirrorRef {
  editor?: HTMLDivElement | null;
  state?: EditorState;
  view?: EditorView;
}
declare const ReactCodeMirror: React.ForwardRefExoticComponent<
  ReactCodeMirrorProps & React.RefAttributes<ReactCodeMirrorRef>
>;
export default ReactCodeMirror;
export interface BasicSetupOptions {
  lineNumbers?: boolean;
  highlightActiveLineGutter?: boolean;
  highlightSpecialChars?: boolean;
  history?: boolean;
  foldGutter?: boolean;
  drawSelection?: boolean;
  dropCursor?: boolean;
  allowMultipleSelections?: boolean;
  indentOnInput?: boolean;
  syntaxHighlighting?: boolean;
  bracketMatching?: boolean;
  closeBrackets?: boolean;
  autocompletion?: boolean;
  rectangularSelection?: boolean;
  crosshairCursor?: boolean;
  highlightActiveLine?: boolean;
  highlightSelectionMatches?: boolean;
  closeBracketsKeymap?: boolean;
  defaultKeymap?: boolean;
  searchKeymap?: boolean;
  historyKeymap?: boolean;
  foldKeymap?: boolean;
  completionKeymap?: boolean;
  lintKeymap?: boolean;
}
import { EditorSelection, SelectionRange } from '@codemirror/state';
import { ViewUpdate } from '@codemirror/view';
export interface Statistics {
  /** Get the number of lines in the editor. */
  lineCount: number;
  /** total length of the document */
  length: number;
  /** Get the proper [line-break](https://codemirror.net/docs/ref/#state.EditorState^lineSeparator) string for this state. */
  lineBreak: string;
  /** Returns true when the editor is [configured](https://codemirror.net/6/docs/ref/#state.EditorState^readOnly) to be read-only. */
  readOnly: boolean;
  /** The size (in columns) of a tab in the document, determined by the [`tabSize`](https://codemirror.net/6/docs/ref/#state.EditorState^tabSize) facet. */
  tabSize: number;
  /** Cursor Position */
  selection: EditorSelection;
  /** Make sure the selection only has one range. */
  selectionAsSingle: SelectionRange;
  /** Retrieves a list of all current selections. */
  ranges: readonly SelectionRange[];
  /** Get the currently selected code. */
  selectionCode: string;
  /**
   * The length of the given array should be the same as the number of active selections.
   * Replaces the content of the selections with the strings in the array.
   */
  selections: string[];
  /** Return true if any text is selected. */
  selectedText: boolean;
}
export declare const getStatistics: (view: ViewUpdate) => Statistics;

Development

  1. Install dependencies
$ npm install       # Installation dependencies
$ npm run build     # Compile all package
  1. Development @uiw/react-codemirror package:
$ cd core
# listen to the component compile and output the .js file
# listen for compilation output type .d.ts file
$ npm run watch # Monitor the compiled package `@uiw/react-codemirror`
  1. Launch documentation site
npm run start

Related

Contributors

As always, thanks to our amazing contributors!

Made with contributors.

License

Licensed under the MIT License.

Frequently asked questions

Is react-codemirror free to use?

react-codemirror is open source under the MIT licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does react-codemirror do?

CodeMirror 6 component for React. @codemirror https://uiwjs.github.io/react-codemirror/

What is react-codemirror written in?

react-codemirror is primarily written in TypeScript. Its source is publicly available at https://github.com/uiwjs/react-codemirror, and it has 2,258 GitHub stars.