JavaScript/TypeScript language server

This is a language server for JavaScript and TypeScript that adheres to the Language Server Protocol (LSP). It uses TypeScript's LanguageService to perform source code analysis.

Getting started

1. npm install
2. node_modules/.bin/tsc
3. node build/language-server.js

To try it in Visual Studio Code, install the vscode-client extension and then open up a .ts file.

Development

Run node_modules/.bin/tsc --watch.

Tests

Run npm test or yarn test.

Command line arguments

• -p, --port specifies port to use, default one is 2089
• -s, --strict enables strict mode where server expects all files to be receives in didOpen notification requests.

Supported LSP requests

initialize

In strict mode we expect rootPath to be equal file:/// while in non-strict mode VSCode usually sends absolute file URL. In both modes does not track existence of calling process.

exit

Implementation closes underlying communication channel

shutdown

Does nothing opposite to LSP specification that expects server to exit

textDocument/hover

textDocument/definition

textDocument/references

workspace/symbols

Introduces limit parameter to limit number of symbols to return

Differences from LSP protocol specification

In strict mode LSP server does not touches underlying file system, instead it uses addition to LSP protocol to fetch information about workspace structure and files content by sending proprietary fs/... requests back to the caller (fs/readDir, fs/readFile) and keeping results in memory.

Custom TypeScript compiler

We are using forked copy of TypeScript compiler to achieve the following goals:

• Add ability to append files on demand. Instead of parsing and analyzing the whole workspace, we are adding files on demand. For example, to extract hover information we only need to add explicitly one file (compiler will implicitly add all the imports and references)
• Allow searching for workspace symbols without a query string specified. Standard TypeScript's method returns no results for empty query while our modification returns first N symbols. We are working to propose our changes into TypeScript upstream repository.

Known issues

• You need to disable VSCode's built-in TypeScript support to avoid weird conflicts on TypeScript files (double hover tooltips, etc.). There's a hacky way to do this: add the setting {"typescript.tsdk": "/dev/null"} to your VSCode user or workspace settings.