Allow --emitDeclarationOnly flag to be passed in --build · Issue #51164 · microsoft/TypeScript (original) (raw)

Suggestion

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emitDeclarationOnly build mode flag

✅ Viability 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, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

This is split off of #25613 after some internal discussion; in --build, most flags are disabled, but it would be convenient to be able to specify --emitDeclarationOnly (true/false).

I'd like to be able to specify --emitDeclarationOnly=false in build mode for the module conversion, which lets us choose whether or not to emit JS or not (for continuous testing of a non-bundled mode); right now I'm using a hack that modifies the config before building and then restores it, which is error-prone when the build is canceled via Ctrl+C.

It's my understanding from our discussion that this flag should be doable, but not without a good bit of changes to what tsbuildinfo and such contain.