CODEWITHSUNDEEP
typescript
born2net
born2net

Reputation: 24953

Why do pure Typescript projects include .d.ts definitions?

Why do Typescript projects include .d.ts definitions... seems counter productive?

If a library is already developed in TypeScript (like Angular2 let's say), and the TS transpiler can use the source .ts files for intellisence, why do I keep seeing in TS projects .d.ts file being included?

Now sure you can easily generate .d.ts definition via the tsd executable, but I can't see the logic.

regards,

Sean

Upvotes: 2

Views: 351

Answers (1)

Richard Szalay
Richard Szalay

Reputation: 84744

It comes down to distribution. Referencing a project via npm/bower provides a "main" file that is javascript, not typescript. As such, it makes most sense for the compilation output of a Typescript project to be:

a) The transpiled javascript file, possibly minified

b) A .d.ts file describing the type annotations (kind of like a header file in C)

It wouldn't make much sense to distribute in typescript since it either would prevent javascript projects from using it, or would necessitate a separate typescript version of the npm package.

Upvotes: 5

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