tsserver-lean

lean-tsserver

Implements a tiny sub-set of tsserver, also using different internal APIs. Its reason d'etré is to i) emit diagnostics for a particular TypeScript module; ii) doing the least amount of work possible.

High-level working description

Whenever a request for diagnostics for module a.ts is issued, it finds a.ts' project , and creates a TypescriptProject and a ProjectService for the a.ts' project. The former is essentially a wrapper to 's config options (references, fileNames, compilerOptions, etc), while the latter is a wrapper to LanguageService.

So, the overview of the process becomes:

1. We find and resolve all of a.ts' direct dependencies
2. For all of those dependencies, emit their declaration files; here, if the import statement is a named specifier (import x from 'project/a/b'), we only emit for b.ts
3. Create/read from memory a.ts' ProjectService
4. Call projectService.languageService.getSemanticDiagnostic and languageService.getSyntacticDiagnostic
5. Immediately write to stdout through a callback

Supported commands

Type check a module

{ "command": "geterr", "type": "request", "seq": 0, "arguments": { "files": ["path/a/.ts", "path/b/.ts"] } }

{ "command": "geterr", "type": "request", "seq": 0, "arguments": { "files": ["/workspaces/client-web/packages/hybridspace/hybridspace-places-selector/src/components/PlacesFinderResult.tsx"] } }

Handshake

Used as a first message sent to stdout to indicate a successful start-up.

{ "command": "handhsake", "type": "request", "seq": 0 }