Compiler API to resolve path from ImportDeclaration

[longlho]

Hi there, since TS supports paths in tsconfig.json, is there an API in the compiler (Program, CompilerHost or something) to programmatically resolve real path of an import?

I wrote this transformer https://github.com/longlho/ts-transform-css-modules and it's tripping up on paths that are aliased in tsconfig.json, e.g:

import * as css from 'alias/foo.css'

tsconfig.json

{
  "compilerOptions": {
    "paths": {
      "alias/*": "../../../some_location/*"
    }
  }
}

I can try to manually reconstruct TS resolver but rather not to.

Thanks!

[ajafff]

ts.resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;

For your use case you can ignore the last parameter redirectedReference.
The cache if needed can be created using

ts.createModuleResolutionCache(currentDirectory: string, getCanonicalFileName: (s: string) => string): ModuleResolutionCache;

[longlho]

Thanks a lot for the help! I gave that a try but unfortunately .css is not a valid TS module extension & looks like failedLookupLocations is internal so I can work off of the result :(

[HoldYourWaffle]

Now that the original question has been answered, wouldn't this be a duplicate of #28770?