Configuring a basic TypeScript composite project

Sometimes I forget the cleanest way to configure a tsconfig composite project with separate tsconfigs for src and test. Here’s the latest template that I use. tsc --showConfig is helpful to validate that it’s doing the right thing.

This configuration is pretty straightforward:

• source in src is emitted to dist
• tests in test will be run via ts-node or similar, so they do not need to be emitted.
• anything else, such as ts-node dev scripts or an ./examples directory, is handled by the root tsconfig file, and is not compiled.

tsconfig.json

{
    // If in a monorepo, extend from the base config
    "extends": "../../tsconfig.json",
    "references": [
        {
            "path": "src"
        },
        {
            "path": "test"
        }
    ],
    // Exclude references and emitted output
    "exclude": ["src", "test", "dist"],
    "compilerOptions": {
        "composite": true,
        "rootDir": ".",
        
        // We can't pass "noEmit" in incremental mode, but this is close enough.
        "outDir": ".tmp/tsc/root",
        "emitDeclarationOnly": true
    }
}

src/tsconfig.json

{
    "extends": "../tsconfig.json",
    "exclude": [],
    "compilerOptions": {
        "rootDir": ".",
        "outDir": "../dist",
        "emitDeclarationOnly": false
    }
}

test/tsconfig.json

{
    "extends": "../tsconfig.json",
    "references": [
        {
            "path": "../src"
        }
    ],
    "exclude": [],
    "compilerOptions": {
        "rootDir": ".",
        "outDir": "../.tmp/tsc/test"
    }
}