Function createModuleResolver

packages/typescript/src/moduleResolution.ts:28–60

(
  ts: typeof typescript,
  host: ModuleResolverHost,
  filter: ReturnType<CreateFilter>
)

 * with methods for sanitizing filenames and getting compiler options.
 */
export default function createModuleResolver(
  ts: typeof typescript,
  host: ModuleResolverHost,
  filter: ReturnType<CreateFilter>
): Resolver {
  const compilerOptions = host.getCompilationSettings();
  const cache = ts.createModuleResolutionCache(
    process.cwd(),
    host.getCanonicalFileName,
    compilerOptions
  );
  const moduleHost = { ...ts.sys, ...host };

  return (moduleName, containingFile, redirectedReference, mode) => {
    const { resolvedModule } = ts.resolveModuleName(
      moduleName,
      containingFile,
      compilerOptions,
      moduleHost,
      cache,
      redirectedReference,
      mode
    );
    /**
     * If the module's path contains 'node_modules', ts considers it an external library and refuses to compile it,
     * so we have to change the value of `isExternalLibraryImport` to false if it's true
     * */
    if (resolvedModule?.isExternalLibraryImport && filter(resolvedModule?.resolvedFileName)) {
      resolvedModule.isExternalLibraryImport = false;
    }
    return resolvedModule;
  };
}