Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

lsp-editor-adapter (alpha)

A library that automatically presents IDE-like elements for code editors in the browser using the the Language Server Protocol.

Currently, you can connect a CodeMirror document to a language server over WebSockets. Future work will support language servers running in-browser, such as via Service Worker, and also support the Ace editor.

This library is in development. Opening issues and pull requests is greatly appreciated!


The following features are all automatically configured once connected to a language server:

  • Intellisense autocomplete
  • Signature completion
  • Hover tooltips
  • Highlighting matching symbols in document
  • Linting or syntax errors
  • Within the same file: Go to Definition, Type Definition, and Find References

All other features of the language server are not currently supported, but if you would like to add support, please submit a pull request!


These screenshots show the current state of the library:


screenshot 2019-01-21 01 03 47


screenshot 2019-01-26 17 08 32

screenshot 2019-01-27 13 47 23

screenshot 2019-01-27 13 47 36

screenshot 2019-01-27 13 48 11


Current requirements:

  • Language server running on a web socket connection, such as jsonrpc-ws-proxy
  • CodeMirror editor with the show-hint addon included
  • Ability to import an ES6 module, which the library is packaged as

Example installation and connection:

import * as CodeMirror from 'codemirror';
// You are required to install the show-hint addon
import 'codemirror/addon/hint/show-hint.css';
import 'codemirror/addon/hint/show-hint';

// Each adapter can have its own CSS
import 'lsp-editor-adapter/lib/codemirror-lsp.css';
import { LspWsConnection, CodeMirrorAdapter } from 'lsp-editor-adapter';

let editor = CodeMirror(document.querySelector('.editor'), {
  value: 'hello world',

  // Optional: You can add a gutter for syntax error markers
  gutters: ['CodeMirror-lsp']

// Take a look at how the example is configured for ideas
let connectionOptions = {
  // Required: Web socket server for the given language server
  serverUri: 'ws://localhost:8080/html',
  // The following options are how the language server is configured, and are required
  rootUri: 'file:///path/to/a/directory',
  documentUri: 'file:///path/to/a/directory/file.html',
  documentText: () => editor.getValue(),
  languageId: 'html',

// The WebSocket is passed in to allow testability
let lspConnection = new LspWsConnection(editor)
  .connect(new WebSocket('ws://localhost:8080'));

// The adapter is what allows the editor to provide UI elements
let adapter = new CodeMirrorAdapter(lspConnection, {
  // UI-related options go here, allowing you to control the automatic features of the LSP, i.e.
  suggestOnTriggerCharacters: false
}, editor);

// You can also provide your own hooks:
lspConnection.on('error', (e) => {

// You might need to provide your own hooks to handle navigating to another file, for example:
lspConnection.on('goTo', (locations) => {
  // Do something to handle the URI in this object

// To clean up the adapter and connection:

Running the example

A fully-functional example project which runs three language servers and allows editing all three files is available at /example

To run the example:

cd example
npm install
npm run start

then visit localhost:4000


To develop against this library, and see updates in the example, run both of these:

# From parent directory
npx webpack --watch
# From example directory
npm run dev

To run library tests, there are two options:

npm test
npm run test-dev

test-dev will watch the source code and rerun tests in the background


Connects language servers with the CodeMirror editor







No releases published


No packages published