typescript-glob-override-plugin

TypeScript Language Service plugin that enables specific compiler options for files matching glob patterns — without changing the project-wide tsconfig.json.

Useful for incrementally introducing strict checks into a large codebase.

Install

npm install --save-dev typescript-glob-override-plugin
# or
yarn add -D typescript-glob-override-plugin

Setup

Add the plugin to your tsconfig.json:

{
  "compilerOptions": {
    "plugins": [
      {
        "name": "typescript-glob-override-plugin",
        "files": [
          "a/**/*.ts",
          "b/**/*.ts"
        ],
        "compilerOptions": {
          "noImplicitOverride": true,
          "strictNullChecks": true,
          "strictFunctionTypes": true,
          "noImplicitAny": true
        }
      }
    ]
  }
}

VS Code

Make sure VS Code uses the workspace TypeScript version (not the built-in one):

1. Open the Command Palette (Cmd+Shift+P)
2. Run TypeScript: Select TypeScript Version
3. Choose Use Workspace Version

Or add to .vscode/settings.json:

{
  "typescript.tsdk": "node_modules/typescript/lib",
  "typescript.preferences.allowLocalPluginLoads": true
}

Configuration

| Field | Type | Required | Description | |-------|------|----------|-------------| | files | string[] | Yes | Glob patterns relative to the tsconfig.json directory. Files matching any pattern will have compilerOptions applied. | | compilerOptions | object | Yes | Any valid TypeScript compiler options to overlay on matched files. Common values: noImplicitOverride, strictNullChecks, strictFunctionTypes, noImplicitAny, strict. |

Glob syntax

| Pattern | Matches | |---------|---------| | src/foo/**/*.ts | All .ts files anywhere under src/foo/ | | src/**/*.ts | All .ts files anywhere under src/ | | src/foo/*.ts | .ts files directly inside src/foo/ (not nested) | | src/foo/bar.ts | Exactly src/foo/bar.ts |

CLI: tsc-override

The package ships a tsc-override command that enforces the glob-based rules at build time / in CI — as a single drop-in replacement for tsc.

# Check all files using tsconfig.json in the current directory
tsc-override

# Point at a specific tsconfig
tsc-override --project path/to/tsconfig.json
tsc-override -p path/to/tsconfig.json

tsc-override checks every file in the project in one pass, routing each to the correct compiler options:

| File | Options used | Errors reported | |------|-------------|-----------------| | Matches a files glob | base options + plugin compilerOptions | Yes | | Does not match any glob | base options (original tsconfig.json) | Yes |

Both programs include all project files so cross-file type inference is correct. The override options never leak into non-matched files, which is important when the override is more lenient than the base (e.g. removing strictNullChecks for a transitional directory).

Exit codes: 0 (all files passed) or 1 (errors found, or a configuration error).

Example CI integration

# .github/workflows/typecheck.yml
- run: tsc-override    # replaces tsc; also enforces per-glob overrides

How it works

The plugin creates a second TypeScript Language Service backed by a proxy LanguageServiceHost whose getCompilationSettings returns the original options merged with compilerOptions. When getSemanticDiagnostics (or getQuickInfoAtPosition) is called for a file that matches one of the files globs, the call is forwarded to this strict service instead of the original one.

The tsc-override CLI uses the same config and glob matching, but drives compilation via two ts.createProgram instances — one with base options (for non-matched files) and one with merged options (for matched files) — both including all project files for correct cross-file type inference. No subprocess is spawned.

Inspired by allegro/typescript-strict-plugin.

Caveats

• strictNullChecks is contagious. Enabling it changes type inference for the whole program (including non-matched files), which may surface extra errors in strict files that import from non-matched ones.
• First load is slow. The strict LanguageService builds its own Program on first use. For large projects this may take a few seconds; subsequent calls are fast.

License

MIT