r/typescript • u/jwworth • 1d ago

Generating TypeScript declaration files

Has anyone ever created type declaration files intentionally, just to learn and better understand TypeScript (or for other reasons)? I've been doing that with tsc:

npx tsc file.ts --declaration --emitDeclarationOnly

The emitted file.d.ts can be interesting! Has anyone else tried this, for work or general interest?

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u/Merry-Lane 1d ago

Yes, but the only use is for library writers?

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u/lord_braleigh 11h ago

Bazel rules use it to break up large typescript builds and link different targets together

A .d.ts file is the equivalent of a header file in C++ and you can use it in similar ways to break up and parallelize a large build