Suggestion: a --noEmitJS compiler option

[mcmath]

The problem

It is sometimes useful to set different compiler options for .js files and .d.ts files. For example, I often want to set --removeComments for JavaScript outputs but not for declaration files. This can currently be achieved by building a project with --declaration and --removeComments enabled, removing emitted .js files, and then building the project without those options:

tsc --declaration --removeComments && rimraf "dest/**/*.js" && tsc

This is convoluted and wasteful. Of course, there are always tools like Gulp, but it would be nice to have a solution using just the tsc command.

A solution: a --noEmitJS compiler option

I would like to see a --noEmitJS compiler option. Like --noEmit, it would suppress emitted JavaScript files, but unlike --noEmit, it would still emit sourcemaps and declaration files if the relevant compiler options are enabled. The above could be achieved like so:

tsc && tsc --declaration --removeComents --noEmitJS

This is nicer. It would also cover any other scenarios where different options are required for either declarations or sourcemaps.

[mhegazy]

Duplicate of #13318

[nojvek]

@mhegazy I understand you've marked this as duplicate of --removeComments option but it doesn't seem like a duplicate. Generating only .d.ts files is a very legit use-case. noEmitJs becomes even more useful when you want to generate typings for pure js project with checkJs, declarations and allowJs enabled.

I understand allowJs + declarations is not supported but I understand it will soon be supported.