node-typescript-support

Multi tsconfig aware TypeScript support for Node.js.

Getting started

Install the library as a dev dependency:

yarn add node-typescript-support --dev

Then, use it as follows:

node -r node-typescript-support/register ./my-script.ts

Or, in your code:

import 'node-typescript-support/register';

Why?

I recently experimented with a neat project setup where I have one tsconfig.json in my src folder, and a second tsconfig.json in my test folder.

Each config created a different type environment by explictly specifying which @types packages are included (via compilerOptions->types).

So while my tests had access to @types/mocha and its globals, my src folder knew nothing of describe() and it().

The above setup gave me type isolation between folders sharing the same node_modules.

For better development velocity, I quickly wanted a TypeScript Node.js integration that supports this setup, and would give me proper type checking per environment. That need led to this library.

How?

The node-typescript-support/register end-point registers this library's TypeScriptNodeExtension for the .ts and .tsx file extensions. It uses require.extensions to do so.

For each .ts or .tsx file, the extension finds the closest tsconfig.json. For each config, it instanciates a separate TypeScript Language Service and uses that service to transpile and type-check the file.

tsconfig.json lookup is done once per directory (cached for the second lookup in that directory). There is one Lanaguage Service per tsconfig.json, and all running services share a document registry.

If no tsconfig.json is found for a typescript file, this integration transpiles it directly using the following Node 8+ friendly compiler options:

export const defaultCompilerOptions: ts.CompilerOptions = {
    target: ts.ScriptTarget.ES2017,
    module: ts.ModuleKind.CommonJS,
    jsx: ts.JsxEmit.React
    moduleResolution: ts.ModuleResolutionKind.NodeJs,
    inlineSourceMap: true
}