require-outdir-when-emitting

Require compilerOptions.outDir when the project emits JavaScript output, to prevent compiled files from being written next to source files.

Targeted pattern scope

The compilerOptions.outDir, compilerOptions.noEmit, and compilerOptions.emitDeclarationOnly fields in any tsconfig*.json file.

What this rule reports

This rule reports when a tsconfig.json is configured to emit JavaScript (i.e., noEmit is absent or false, and emitDeclarationOnly is absent or false) but outDir is not specified.

Why this rule exists

Without outDir, TypeScript writes compiled .js files alongside their corresponding .ts source files in the same directory. This leads to:

Source directories filled with generated JavaScript that should not be committed.
Build tool confusion when both .ts and .js files exist with the same name.
Incomplete .gitignore coverage because outputs are interspersed with sources.
Unexpected behavior when include patterns match both the source .ts and the generated .js.

Setting outDir to a dedicated output directory such as ./dist or ./build keeps the source tree clean and makes the build output predictable.

❌ Incorrect

{
    "compilerOptions": {
        "target": "ES2022",
        "module": "NodeNext"
    }
}

Without outDir or noEmit, TypeScript writes .js files next to .ts files.

✅ Correct

{
    "compilerOptions": {
        "target": "ES2022",
        "module": "NodeNext",
        "outDir": "./dist"
    }
}

Or, for a type-check-only config:

{
    "compilerOptions": {
        "noEmit": true
    }
}

When not to use it

Disable this rule for scripts-only projects where all TypeScript files are run via ts-node or similar tools and no compilation step is needed.

Package documentation

Rule catalog ID: R022

Targeted pattern scope​

What this rule reports​

Why this rule exists​

❌ Incorrect​

✅ Correct​

When not to use it​

Package documentation​

Further reading​