This repository now host multiple npm packages under one roof:

• monaco-languageclient to connect Monaco editor with language servers.
• vscode-ws-jsonrpc which implements communication between a jsonrpc client and server over WebSocket.
• monaco-editor-wrapper for building monaco editor application driven by configuration
• monaco-editor-react puts a react cloack over monaco-editor-wrapper
• monaco-languageclient-examples provides the examples which allows to use them externally.

Click here for a detail explanation how to connect the Monaco editor to your language server.

• Monaco Language Client, VSCode WebSocket Json RPC, Monaco-Editor-Wrapper, Monaco-Editor-React and examples
  • Changelogs, project history and compatibility
  • Getting started
    • Vite dev server
  • Usage
  • Examples Overview
    • Main Examples
    • Example usage
      • Server processes
        • JSON Language Server
        • Pyright Language Server
        • Groovy Language Server
    • Verification Examples & Usage
    • VSCode integration
  • Featured projects
  • Troubleshooting
    • General
    • Dependency issues: monaco-editor / @codingame/monaco-vscode-api / @codingame/monaco-vscode-editor-api
    • Volta
    • Vite dev server troubleshooting
    • Serve all files required
    • Bad Polyfills
      • buffer
    • monaco-editor and react
    • pnpm
  • Licenses

CHANGELOGs for each project are available from the linked location:

• CHANGELOG for monaco-languageclient is found here
• CHANGELOG for vscode-ws-jsonrpc is found here
• CHANGELOG for monaco-editor-wrapper is found here
• CHANGELOG for @typefox/monaco-editor-react is found here
• CHANGELOG for monaco-languageclient-examples is found here

Important Project changes and notes about the project's history are found here.

You find the monaco-editor, vscode, @codingame/monaco-vscode-api and @codingame/monaco-vscode-editor-api compatibility table here.

On your local machine you can prepare your dev environment as follows. At first it is advised to build everything. Or, use a fresh dev environment in Gitpod by pressing the code now badge above. Locally, from a terminal do:

git clone https://github.com/TypeFox/monaco-languageclient.git
cd monaco-languageclient
npm i
# Cleans-up, compiles and builds everything
npm run build

Start the Vite dev server. It serves all client code at localhost. You can go to the index.html and navigate to all client examples from there. You can edit the client example code directly (TypeScript) and Vite ensures it automatically made available:

npm run dev
# OR: this clears the cache and has debug output
npm run dev:debug

As this is a npm workspace the main package.json contains script entries applicable to the whole workspace like watch, build and lint, but it also contains shortcuts for launching scripts from the childe packages like npm run build:examples.

If you want to change the libries and see this reflected directly, then you need to run the watch command that compiles all TypeScript files form both libraries and the examples:

npm run watch

Please look at the respective section in the packages:

• Usage for monaco-languageclient is found here
• Usage for vscode-ws-jsonrpc is found here
• Usage for monaco-editor-wrapper is found here
• Usage for @typefox/monaco-editor-react is found here

The examples demonstrate mutliple things:

• How monaco-languageclient is use by monaco-edtior-wrapper or @typefox/monaco-editor-react to have an editor that is connected to a language server either running in the browser in a web worker or vscode-ws-jsonrpc. is used to an external process via web-socket.
• How different language servers can be intergrated in a common way, so they can communicate via web-socket to the front-end running in the browser.

• JSON Language client and language server example:

  • The json-server runs an external Node.js Express app where web sockets are used to enable communication between the language server process and the client web application (see JSON Language Server).
  • The json-client contains the monaco-editor-wrapper app which connects to the language server and therefore requires the node server app to be run in parallel.

• Python Language client and pyright language server example:

  • The python-server runs an external Node.js Express app where web sockets are used to enable communication between the language server process and the client web application (see Pyright Language Server).
  • The python-client contains the monaco-editor-wrapper app which connects to the language server and therefore requires the node server app to be run in parallel.

• Groovy Language client and language server example:

  • The groovy-server runs an external Java app where web sockets are used to enable communication between the language server process and the client web application (Groovy Language Server).
  • The groovy-client contains the monaco-editor-wrapper app which connects to the language server and therefore requires the node server app to be run in parallel.
  • It is also possible to use a @typefox/monaco-editor-react app to connect to the server.

• Langium examples (here client and server communicate via vscode-languageserver-protocol/browser instead of a web socket used in the three examples above:

  • Langium grammar DSL: It contains both the language client and the langauge server (web worker). Here you can chose beforehand if the wrapper should be started in classic or extended mode.
  • Statemachine DSL (created with Langium): It contains both the language client and the langauge server (web worker).
    • It is also possible to use a @typefox/monaco-editor-react app to connect to the server.

• browser example demonstrates how a monaco-editor-wrapper can be combined with a language service written in JavaScript. This example can now be considered legacy as the web worker option eases client side language server implementation and separation, but it still shows a valid way to achieve the desired outcome.

• Typescript Language support

• Multi-editor usage

For the json-client, react-client or the client-webpack examples you need to ensure the json-server example is running:

# start the express server with the language server running in the same process.
npm run start:example:server:json

For the python-client example you need to ensure the python-server example is running:

# start the express server with the language server running as external node process.
npm run start:example:server:python

For the groovy-client example you need to ensure the groovy-server example is running. There are two options available:

• Preferred option: Use docker-compose which does not require any manual setup (Java/Gradle). From the project root run docker-compose -f ./packages/examples/resources/groovy/docker-compose.yml up -d. First start up will take longer as the container is built. Use docker-compose -f ./packages/examples/resources/groovy/docker-compose.yml down to stop it.

• Secondary option (not recommended): Groovy Language Server self-built instructions

None of the verification examples is part of the npm workspace. Some bring substantial amount of npm dependencies that pollute the main node_modules dependencies and therefore these examples need to be build and started independently. All verifaction examples re-uses the code form the json client example and therefore require the json server to be started.

• angular verification example: Before March 2024 this was located in a separate repository. If you want to test it, Please do: cd verify/angular && npm run verify. It serves the client here: http://localhost:4200.

• webpack verification example demonstrates how bundling can be achieved with webpack. You find the configuration here: webpack.config.js. Please do: cd verify/webpack && npm run verify. It serves the client here: http://localhost:8081.

• vite verification example demonstrates how bundling can be achieved with vite. There is no configuration required Please do: cd verify/vite && npm run verify. It serves the client here: http://localhost:8082.

• pnpm verification example demonstrates that the project can be build with vite, but pnpm is used instead of npm. Please do: cd verify/pnpm && pnpm run verify. It serves the client here: http://localhost:8083.

• yarn verification exampledemonstrates that the project can be build with vite, but yarn is used instead of npm. Please do: cd verify/yarn && yarn run verify. It serves the client here: http://localhost:8083.

You can as well run vscode tasks to start and debug the server in different modes and the client.

• JSONA Editor: Showcase (GitHub)
• monaco-editor-wrapper: Showcase (GitHub)

Whenever you used monaco-editor, vscode, monaco-languageclient, monaco-editor-wrapper or @typefox/monaco-editor-react ensure they are imported before you do any monaco-editor or vscode api related intialization work or start using it. Please check the our python language client example to see how it should be done.

If you have mutiple, possibly hundreds of compile errors resulting from missing functions deep in monaco-editor or vscode then it is very likely your package-lock.json or node_modules are dirty. Remove both and do a fresh npm install. Always npm list monaco-editor is very useful. If you see different or errornous versions, then this is an indicator something is wrong.

There are Volta instructions in the package.json files. When you have Volta available it will ensure the exactly specified node and npm versions are used.

When you are using vite for development please be aware of this recommendation.

If you see the problem Assertion failed (There is already an extension with this id) you likely have mismatching dependencies defined for vscode / @codingame/monaco-vscode-api. You should fix this or add the following entry to your vite config:

resolve: {
  dedupe: ['vscode']
}

@codingame/monaco-vscode-api requires json and other files to be served. In your project's web-server configuration you have to ensure you don't prevent this.

If you see an error similar to the one below:

Uncaught Error: Unexpected non—whitespace character after JSON at position 2

SyntaxError: Unexpected non—whitespace character after JSON at position 2
    at JSON. parse («anonymous>)

It is very likely you have an old version of buffer interfering (see #538 and #546). You can enforce a current version by adding a resolution as shown below to your projects' package.json.

"resolutions": {
  "buffer": "~6.0.3",
}

We recommend you now use typefox/monaco-editor-react.

But if you need to use @monaco-editor/react, then add the monaco-editor import at the top of your editor component file source:

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

loader.config({ monaco });

If you use pnpm, you have to add vscode / @codingame/monaco-vscode-api as direct dependency (you find the compatibility table here, otherwise the installation will fail.

"vscode": "npm:@codingame/monaco-vscode-api@~4.3.2"

• monaco-languageclient: MIT
• vscode-ws-jsonrpc: MIT
• monaco-editor-wrapper: MIT
• @typefox/monaco-editor-react: MIT
• monaco-languageclient-examples: MIT