Alias for TypeScript declaration emitting

Search Terms

• alias
• declaration

Suggestion

A way to configuration alias for declaration files.

Use Cases

Related: #10866

I understand that TypeScript team want to leaves module resolving for other tools like Webpack. However, most of the tools are focus on emitting JavaScript. If you want to emit TypeScript declaration, you need to use tsc.

This is important when you want to write library with TypeScript that you need to release declaration files.

For example, in Webpack, babel-loader does not emit declarations, ts-loader and awesome-typescript-loader uses tsc.

Alias is useful for you to write simpler import / export statement.

Examples

index.ts

export * from "~/foo";

index.d.ts

export * from "../../foo";

tsconfig.json

{
  "alias": {
    "~/*": ["src/*"]
  }
}

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Start by comparing the requested transformations in index.ts and index.d.ts, then review the alias configuration example in tsconfig.json and related issue #10866. Done would mean a defined TypeScript configuration mechanism that lets declaration output resolve the configured alias to the intended relative path.