@monaco-editor/react

What is @monaco-editor/react?

@monaco-editor/react is a React component for integrating the Monaco Editor, which is the code editor that powers Visual Studio Code, into React applications. It provides a simple way to embed a powerful code editor with syntax highlighting, IntelliSense, and other advanced features.

What are @monaco-editor/react's main functionalities?

Basic Usage

This code demonstrates how to use the @monaco-editor/react package to embed a basic Monaco Editor instance in a React application. The editor is set to use JavaScript language and the 'vs-dark' theme.

import React from 'react';
import { MonacoEditor } from '@monaco-editor/react';

function App() {
  return (
    <div>
      <MonacoEditor height="90vh" language="javascript" theme="vs-dark" />
    </div>
  );
}

export default App;

Customizing Editor Options

This example shows how to customize the editor options. The options object allows you to configure various aspects of the editor, such as making it read-only, changing the cursor style, and enabling automatic layout.

import React from 'react';
import { MonacoEditor } from '@monaco-editor/react';

function App() {
  const options = {
    selectOnLineNumbers: true,
    roundedSelection: false,
    readOnly: true,
    cursorStyle: 'line',
    automaticLayout: true
  };

  return (
    <div>
      <MonacoEditor height="90vh" language="javascript" theme="vs-dark" options={options} />
    </div>
  );
}

export default App;

Handling Editor Events

This example demonstrates how to handle editor events, such as content changes. The onChange prop is used to pass a callback function that will be called whenever the editor's content changes.

import React from 'react';
import { MonacoEditor } from '@monaco-editor/react';

function App() {
  const handleEditorChange = (value, event) => {
    console.log('Editor content changed:', value);
  };

  return (
    <div>
      <MonacoEditor height="90vh" language="javascript" theme="vs-dark" onChange={handleEditorChange} />
    </div>
  );
}

export default App;

Other packages similar to @monaco-editor/react

react-ace

react-ace is a React component for the Ace editor, another popular code editor. It offers similar features like syntax highlighting, themes, and various editor options. However, Monaco Editor is generally considered more powerful and feature-rich, especially for larger projects.

react-codemirror2

react-codemirror2 is a React component for the CodeMirror editor. It provides a highly customizable code editor with support for many languages and themes. While CodeMirror is lightweight and fast, Monaco Editor offers more advanced features like IntelliSense and better integration with TypeScript.

react-simple-code-editor

react-simple-code-editor is a lightweight code editor component for React. It is built on top of Prism.js for syntax highlighting. While it is simpler and easier to use, it lacks many of the advanced features found in Monaco Editor, such as IntelliSense and comprehensive language support.

README

@monaco-editor/react ·

Monaco Editor for React · use the monaco-editor in any React application without needing to use webpack (or rollup/parcel/etc) configuration files / plugins

---

• :keyboard: rewritten with TypeScript :fire:
• :zap: multi-model editor is already supported; enjoy it :tada:
• :tada: version v4 is here - to see what's new in the new version and how to migrate from v3, please read this doc (also, if you need the old version README, it's here)
• :video_game: the new section Development / Playground has been created - now you can run the playground and play with the internals of the library
• :dizzy: it's already integrated with @monaco-editor/loader

---

Synopsis

Monaco editor wrapper for easy/one-line integration with any React application without needing to use webpack (or any other module bundler) configuration files / plugins. It can be used with apps generated by create-react-app, create-snowpack-app, vite, Next.js or any other app generators - you don't need to eject or rewire them.

Motivation

The monaco-editor is a well-known web technology based code editor that powers VS Code. This library handles the setup process of the monaco-editor and provides a clean API to interact with monaco from any React environment

Demo

Check it out!

Documentation

• Installation
• Introduction
• Usage
  • Simple usage
  • Get value
  • editor instance
  • monaco instance
  • useMonaco
  • loader/config
  • Multi-model editor
  • onValidate
  • Notes
    • For electron users
    • For Next.js users
  • Create your own editor!
• Development / Playground
• Props
  • Editor
  • Diff Editor

Installation

npm install @monaco-editor/react

or

yarn add @monaco-editor/react

or you can use CDN. Here is an example

NOTE: For TypeScript type definitions, this package uses the monaco-editor package as a peer dependency. So, if you need types and don't already have the monaco-editor package installed, you will need to do so

Introduction

Besides types, the library exports Editorand DiffEditor components, as well as the loader utility and the useMonaco hook:

import Editor, { DiffEditor, useMonaco, loader } from '@monaco-editor/react';

Usage

Simple usage

Here is an example of a simple integration of monaco editor with a React project.
You just need to import and render the Editor component:

import React from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  return <Editor height="90vh" defaultLanguage="javascript" defaultValue="// some comment" />;
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

codesandbox

Extended example

import React from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  function handleEditorChange(value, event) {
    // here is the current value
  }

  function handleEditorDidMount(editor, monaco) {
    console.log('onMount: the editor instance:', editor);
    console.log('onMount: the monaco instance:', monaco);
  }

  function handleEditorWillMount(monaco) {
    console.log('beforeMount: the monaco instance:', monaco);
  }

  function handleEditorValidation(markers) {
    // model markers
    // markers.forEach(marker => console.log('onValidate:', marker.message));
  }

  return (
    <Editor
      height="90vh"
      defaultLanguage="javascript"
      defaultValue="// some comment"
      onChange={handleEditorChange}
      onMount={handleEditorDidMount}
      beforeMount={handleEditorWillMount}
      onValidate={handleEditorValidation}
    />
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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Get value

There are two options to get the current value:

1. get the current model value from the editor instance

import React, { useRef } from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  const editorRef = useRef(null);

  function handleEditorDidMount(editor, monaco) {
    editorRef.current = editor;
  }

  function showValue() {
    alert(editorRef.current.getValue());
  }

  return (
    <>
      <button onClick={showValue}>Show value</button>
      <Editor
        height="90vh"
        defaultLanguage="javascript"
        defaultValue="// some comment"
        onMount={handleEditorDidMount}
      />
    </>
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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1. get the current model value via onChange prop

import React from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  function handleEditorChange(value, event) {
    console.log('here is the current model value:', value);
  }

  return (
    <Editor
      height="90vh"
      defaultLanguage="javascript"
      defaultValue="// some comment"
      onChange={handleEditorChange}
    />
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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(get the `DiffEditor` values via `editor` instance)

import React, { useRef } from 'react';
import ReactDOM from 'react-dom';

import { DiffEditor } from '@monaco-editor/react';

function App() {
  const diffEditorRef = useRef(null);

  function handleEditorDidMount(editor, monaco) {
    diffEditorRef.current = editor;
  }

  function showOriginalValue() {
    alert(diffEditorRef.current.getOriginalEditor().getValue());
  }

  function showModifiedValue() {
    alert(diffEditorRef.current.getModifiedEditor().getValue());
  }

  return (
    <>
      <button onClick={showOriginalValue}>show original value</button>
      <button onClick={showModifiedValue}>show modified value</button>
      <DiffEditor
        height="90vh"
        language="javascript"
        original="// the original code"
        modified="// the modified code"
        onMount={handleEditorDidMount}
      />
    </>
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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editor instance

The editor instance is exposed from the onMount prop as a first parameter, the second is the monaco instance

import React, { useRef } from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  const editorRef = useRef(null);

  function handleEditorDidMount(editor, monaco) {
    // here is the editor instance
    // you can store it in `useRef` for further usage
    editorRef.current = editor;
  }

  return (
    <Editor
      height="90vh"
      defaultLanguage="javascript"
      defaultValue="// some comment"
      onMount={handleEditorDidMount}
    />
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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monaco instance

There are three options to get the monaco instance:

1. via onMount/beforeMount

import React, { useRef } from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  const monacoRef = useRef(null);

  function handleEditorWillMount(monaco) {
    // here is the monaco instance
    // do something before editor is mounted
    monaco.languages.typescript.javascriptDefaults.setEagerModelSync(true);
  }

  function handleEditorDidMount(editor, monaco) {
    // here is another way to get monaco instance
    // you can also store it in `useRef` for further usage
    monacoRef.current = monaco;
  }

  return (
    <Editor
      height="90vh"
      defaultLanguage="javascript"
      defaultValue="// some comment"
      beforeMount={handleEditorWillMount}
      onMount={handleEditorDidMount}
    />
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

codesandbox

1. via loader utility

import { loader } from '@monaco-editor/react';

loader.init().then((monaco) => console.log('here is the monaco instance:', monaco));

codesandbox

1. via useMonaco hook

import React from 'react';
import ReactDOM from 'react-dom';

import Editor, { useMonaco } from '@monaco-editor/react';

function App() {
  const monaco = useMonaco();

  useEffect(() => {
    if (monaco) {
      console.log('here is the monaco instance:', monaco);
    }
  }, [monaco]);

  return <Editor height="90vh" defaultValue="// some comment" defaultLanguage="javascript" />;
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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useMonaco

useMonaco is a React hook that returns the instance of the monaco. But there is an important note that should be considered: the initialization process is being handled by the loader utility (the reference of @monaco-editor/loader): that process is being done asynchronously and only once. So, if the first initiator of the initialization is useMonaco hook, the first returned value will be null, due to its asynchronous installation. Just check the returned value of useMonaco

import React, { useEffect } from 'react';
import ReactDOM from 'react-dom';

import Editor, { useMonaco } from '@monaco-editor/react';

function App() {
  const monaco = useMonaco();

  useEffect(() => {
    // do conditional chaining
    monaco?.languages.typescript.javascriptDefaults.setEagerModelSync(true);
    // or make sure that it exists by other ways
    if (monaco) {
      console.log('here is the monaco instance:', monaco);
    }
  }, [monaco]);

  return <Editor height="90vh" defaultValue="// some comment" defaultLanguage="javascript" />;
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

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loader-config

The library exports (named) the utility called loader. Basically, it's the reference of @monaco-editor/loader. By default, monaco files are being downloaded from CDN. There is an ability to change this behavior, and other things concerning the AMD loader of monaco. We have a default config file that you can modify by the way shown below:

import { loader } from '@monaco-editor/react';

// you can change the source of the monaco files
loader.config({ paths: { vs: '...' } });

// you can configure the locales
loader.config({ 'vs/nls': { availableLanguages: { '*': 'de' } } });

// or
loader.config({
  paths: {
    vs: '...',
  },
  'vs/nls': {
    availableLanguages: {
      '*': 'de',
    },
  },
});

use monaco-editor as an npm package

Starting from version v4.4.0 it's possible to use monaco-editor as an npm package; import it from node_modules and include monaco sources into your bundle (instead of using CDN). To make it work you can do the following:

import * as monaco from 'monaco-editor';
import { loader } from '@monaco-editor/react';

loader.config({ monaco });

// ...

NOTE: you should be aware that this may require additional webpack plugins, like monaco-editor-webpack-plugin or it may be impossible to use in apps generated by CRA without ejecting them.

If you use Vite, you need to do this:

import { loader } from '@monaco-editor/react';

import * as monaco from 'monaco-editor';
import editorWorker from 'monaco-editor/esm/vs/editor/editor.worker?worker';
import jsonWorker from 'monaco-editor/esm/vs/language/json/json.worker?worker';
import cssWorker from 'monaco-editor/esm/vs/language/css/css.worker?worker';
import htmlWorker from 'monaco-editor/esm/vs/language/html/html.worker?worker';
import tsWorker from 'monaco-editor/esm/vs/language/typescript/ts.worker?worker';

self.MonacoEnvironment = {
  getWorker(_, label) {
    if (label === 'json') {
      return new jsonWorker();
    }
    if (label === 'css' || label === 'scss' || label === 'less') {
      return new cssWorker();
    }
    if (label === 'html' || label === 'handlebars' || label === 'razor') {
      return new htmlWorker();
    }
    if (label === 'typescript' || label === 'javascript') {
      return new tsWorker();
    }
    return new editorWorker();
  },
};

loader.config({ monaco });

loader.init().then(/* ... */);

codesandbox

NOTE: your passed object will be deeply merged with the default one

Multi-model editor

When you render the Editor component, a default model is being created. It's important to mention that when you change the language or value props, they affect the same model that has been auto-created at the mount of the component. In most cases it's okay, but the developers face problems when they want to implement a multi-model editor to support tabs/files like in IDEs. And previously to handle multiple models they had to do it manually and out of the component. Now, the multi-model API is supported :tada: Let's check how it works. There are three parameters to create a model - value, language and path (monaco.editor.createModel(value, language, monaco.Uri.parse(path))). You can consider last one (path) as an identifier for the model. The Editor component, now, has a path prop. When you specify a path prop, the Editor component checks if it has a model by that path or not. If yes, the existing model will be shown, otherwise, a new one will be created (and stored). Using this technique you can correspond your files with paths, and create a fully multi-model editor. You can open your file, do some changes, choose another file, and when you come back to the first one the previous model will be shown with the whole view state, text selection, undo stack, scroll position, etc. (simple demo)

Here is a simple example: let's imagine we have a JSON like representation of some file structure, something like this:

const files = {
  'script.js': {
    name: 'script.js',
    language: 'javascript',
    value: someJSCodeExample,
  },
  'style.css': {
    name: 'style.css',
    language: 'css',
    value: someCSSCodeExample,
  },
  'index.html': {
    name: 'index.html',
    language: 'html',
    value: someHTMLCodeExample,
  },
};

And here is our simple multi-model editor implementation:

import React from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  const [fileName, setFileName] = useState('script.js');

  const file = files[fileName];

  return (
    <>
      <button disabled={fileName === 'script.js'} onClick={() => setFileName('script.js')}>
        script.js
      </button>
      <button disabled={fileName === 'style.css'} onClick={() => setFileName('style.css')}>
        style.css
      </button>
      <button disabled={fileName === 'index.html'} onClick={() => setFileName('index.html')}>
        index.html
      </button>
      <Editor
        height="80vh"
        theme="vs-dark"
        path={file.name}
        defaultLanguage={file.language}
        defaultValue={file.value}
      />
    </>
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

The properties:

• defaultValue
• defaultLanguage
• defaultPath
• value
• language
• path
• saveViewState

will give you more flexibility in working with a multi-model editor.

NOTE

defaultValue, defaultLanguage, and defaultPath are being considered only during a new model creation
value, language, and path are being tracked the whole time
saveViewState is an indicator whether to save the models' view states between model changes or not

codesandbox

onValidate

onValidate is an additional property. An event is emitted when the content of the current model is changed and the current model markers are ready. It will be fired with the current model markers

import React from 'react';
import ReactDOM from 'react-dom';

import Editor from '@monaco-editor/react';

function App() {
  function handleEditorValidation(markers) {
    // model markers
    markers.forEach((marker) => console.log('onValidate:', marker.message));
  }

  return (
    <Editor
      height="90vh"
      defaultLanguage="javascript"
      defaultValue="// let's write some broken code 😈"
      onValidate={handleEditorValidation}
    />
  );
}

const rootElement = document.getElementById('root');
ReactDOM.render(<App />, rootElement);

codesandbox

It's important to mention that according to monaco-editor, the whole supported languages are divided into two groups:

1. languages that have rich IntelliSense and validation

• TypeScript
• JavaScript
• CSS
• LESS
• SCSS
• JSON
• HTML

1. languages with only basic syntax colorization

• XML
• PHP
• C#
• C++
• Razor
• Markdown
• Diff
• Java
• VB
• CoffeeScript
• Handlebars
• Batch
• Pug
• F#
• Lua
• Powershell
• Python
• Ruby
• SASS
• R
• Objective-C

As you can guess, onValidate prop will work only with the languages from the first group

Notes

For electron users

As a usual React component, this one also works fine with an electron-react environment, without need to have a webpack configuration or other extra things. But there are several cases that developers usually face to and sometimes it can be confusing. Here they are:

1. You see loading screen stuck Usually, it's because your environment doesn't allow you to load external sources. By default, it loads monaco sources from CDN. You can see the default configuration. But sure you can change that behavior; the library is fully configurable. Read about it here. So, if you want to download it from your local files, you can do it like this:

import { loader } from '@monaco-editor/react';

loader.config({ paths: { vs: '../path-to-monaco' } });

1. Based on your electron environment it can be required to have an absolute URL The utility function taken from here can help you to achieve that. Let's imagine you have monaco-editor package installed and you want to load monaco from the node_modules rather than from CDN: in that case, you can write something like this:

function ensureFirstBackSlash(str) {
  return str.length > 0 && str.charAt(0) !== '/' ? '/' + str : str;
}

function uriFromPath(_path) {
  const pathName = path.resolve(_path).replace(/\\/g, '/');
  return encodeURI('file://' + ensureFirstBackSlash(pathName));
}

loader.config({
  paths: {
    vs: uriFromPath(path.join(__dirname, '../node_modules/monaco-editor/min/vs')),
  },
});

There were several issues about this topic that can be helpful too - 1 2 3 4

And if you use electron with monaco and react and have faced an issue different than the above-discribed ones, please let us know to make this section more helpful

For Next.js users

Like other React components, this one also works with Next.js without a hitch. The part of the source that should be pre-parsed is optimized for server-side rendering, so, in usual cases, it will work fine, but if you want to have access, for example, to monaco instance you should be aware that it wants to access the document object, and it requires browser environment. Basically you just need to avoid running that part out of browser environment, there are several ways to do that. The one is described here

And if you use monaco with Next.js and have faced an issue different than the above-described one, please let us know to make this section more helpful

Create your own editor

Under the hood this library uses @monaco-editor/loader that provides a utility called loader. The loader utility is a collection of functions that are being used to setup monaco editor into your browser. loader.init() handles the whole initialization process and returns the instance of the monaco - loader.init().then(monaco => console.log("here is the monaco instance:", monaco)). The Editor component uses this utility, gains access to monaco instance and creates the editor. Here is the implementation of the Editor component. You can use the same technique to create your own Editor. You can just import the loader utility, access to monaco instance, and create your own editor with your own custom logic. The shortest way to do it:

import loader from '@monaco-editor/loader';

loader.init().then((monaco) => {
  const wrapper = document.getElementById('root');
  wrapper.style.height = '100vh';
  const properties = {
    value: 'function hello() {\n\talert("Hello world!");\n}',
    language: 'javascript',
  };

  monaco.editor.create(wrapper, properties);
});

That's all. You can wrap it into a React component, or Vue, or Angular or leave it as vanilla one or whatever you want; it's written in pure js

codesandbox

Development-Playground

It's always important to have a place, where you can play with the internals of the library. The playground is a minimal React app that directly uses the sources of the library. So, if you are going to open a PR, or want to check something, or just want to try the freshest state of the library, you can run the playground and enjoy it

• clone the repository

git clone https://github.com/suren-atoyan/monaco-react.git

• go to the library folder

 cd monaco-react

• install the library's dependencies

 npm install # yarn

• go to the playground

 cd playground

• install the playground's dependencies

npm install # yarn

• and run the playground

npm run dev # yarn dev

monaco-react
├── playground
│   ├── src/      # playground sources
├── src/          # library sources
└── ...

If you want to change something in the library, go to monaco-react/src/..., the library will be automatically re-built and the playground will use the latest build

Props

Editor

Name	Type	Default	Description
defaultValue	string		Default value of the current model
defaultLanguage	string		Default language of the current model
defaultPath	string		Default path of the current model. Will be passed as the third argument to .createModel method - monaco.editor.createModel(..., ..., monaco.Uri.parse(defaultPath))
value	string		Value of the current model
language	enum: ...		Language of the current model (all languages that are supported by monaco-editor)
path	string		Path of the current model. Will be passed as the third argument to .createModel method - monaco.editor.createModel(..., ..., monaco.Uri.parse(defaultPath))
theme	enum: "light" | "vs-dark"	"light"	The theme for the monaco. Available options "vs-dark" | "light". Define new themes by monaco.editor.defineTheme
line	number		The line to jump on it
loading	React Node	"Loading..."	The loading screen before the editor will be mounted
options	object	{}	IStandaloneEditorConstructionOptions
overrideServices	object	{}	IEditorOverrideServices
saveViewState	boolean	true	Indicator whether to save the models' view states between model changes or not
keepCurrentModel	boolean	false	Indicator whether to dispose the current model when the Editor is unmounted or not
width	union: number | string	"100%"	Width of the editor wrapper
height	union: number | string	"100%"	Height of the editor wrapper
className	string		Class name for the editor container
wrapperProps	object	{}	Props applied to the wrapper element
beforeMount	func	noop	Signature: function(monaco: Monaco) => void An event is emitted before the editor is mounted. It gets the monaco instance as a first argument
onMount	func	noop	Signature: function(editor: monaco.editor.IStandaloneCodeEditor, monaco: Monaco) => void An event is emitted when the editor is mounted. It gets the editor instance as a first argument and the monaco instance as a second
onChange	func		Signature: function(value: string | undefined, ev: monaco.editor.IModelContentChangedEvent) => void An event is emitted when the content of the current model is changed
onValidate	func	noop	Signature: function(markers: monaco.editor.IMarker[]) => void An event is emitted when the content of the current model is changed and the current model markers are ready

DiffEditor

Name	Type	Default	Description
original	string		The original source (left one) value
modified	string		The modified source (right one) value
language	enum: ...		Language for the both models - original and modified (all languages that are supported by monaco-editor)
originalLanguage	enum: ...		This prop gives you the opportunity to specify the language of the original source separately, otherwise, it will get the value of the language property
modifiedLanguage	enum: ...		This prop gives you the opportunity to specify the language of the modified source separately, otherwise, it will get the value of language property
originalModelPath	string		Path for the "original" model. Will be passed as a third argument to .createModel method - monaco.editor.createModel(..., ..., monaco.Uri.parse(originalModelPath))
modifiedModelPath	string		Path for the "modified" model. Will be passed as a third argument to .createModel method - monaco.editor.createModel(..., ..., monaco.Uri.parse(modifiedModelPath))
keepCurrentOriginalModel	boolean	false	Indicator whether to dispose the current original model when the DiffEditor is unmounted or not
keepCurrentModifiedModel	boolean	false	Indicator whether to dispose the current modified model when the DiffEditor is unmounted or not
theme	enum: "light" | "vs-dark"	"light"	The theme for the monaco. Available options "vs-dark" | "light". Define new themes by monaco.editor.defineTheme
line	number		The line to jump on it
loading	React Node	"Loading..."	The loading screen before the editor will be mounted
options	object	{}	IDiffEditorConstructionOptions
width	union: number | string	"100%"	Width of the editor wrapper
height	union: number | string	"100%"	Height of the editor wrapper
className	string		Class name for the editor container
wrapperProps	object	{}	Props applied to the wrapper element
beforeMount	func	noop	Signature: function(monaco: Monaco) => void An event is emitted before the editor mounted. It gets the monaco instance as a first argument
onMount	func	noop	Signature: function(editor: monaco.editor.IStandaloneCodeEditor, monaco: Monaco) => void An event is emitted when the editor is mounted. It gets the editor instance as a first argument and the monaco instance as a second

License

MIT

Changelog

4.6.0

Oct 6, 2023

• Editor/DiffEditor: use 'use client' on top of Editor.tsx and DiffEditor.tsx
• loader: update @monaco-editor/loader version (1.4.0)
• playground: use createRoot for bootstrapping