Function resolveBuildOutputs

packages/vite/src/node/build.ts:1029–1082

(
  outputs: OutputOptions | OutputOptions[] | undefined,
  libOptions: LibraryOptions | false,
  logger: Logger,
)

}

export function resolveBuildOutputs(
  outputs: OutputOptions | OutputOptions[] | undefined,
  libOptions: LibraryOptions | false,
  logger: Logger,
): OutputOptions | OutputOptions[] | undefined {
  if (libOptions) {
    const libHasMultipleEntries =
      typeof libOptions.entry !== 'string' &&
      Object.values(libOptions.entry).length > 1
    const libFormats =
      libOptions.formats ||
      (libHasMultipleEntries ? ['es', 'cjs'] : ['es', 'umd'])

    if (!Array.isArray(outputs)) {
      if (libFormats.includes('umd') || libFormats.includes('iife')) {
        if (libHasMultipleEntries) {
          throw new Error(
            'Multiple entry points are not supported when output formats include "umd" or "iife".',
          )
        }

        if (!libOptions.name) {
          throw new Error(
            'Option "build.lib.name" is required when output formats include "umd" or "iife".',
          )
        }
      }

      return libFormats.map((format) => ({ ...outputs, format }))
    }

    // By this point, we know "outputs" is an Array.
    if (libOptions.formats) {
      logger.warn(
        colors.yellow(
          '"build.lib.formats" will be ignored because "build.rolldownOptions.output" is already an array format.',
        ),
      )
    }

    outputs.forEach((output) => {
      if (
        (output.format === 'umd' || output.format === 'iife') &&
        !output.name
      ) {
        throw new Error(
          'Entries in "build.rolldownOptions.output" must specify "name" when the format is "umd" or "iife".',
        )
      }
    })
  }

  return outputs
}

const warningIgnoreList = [`CIRCULAR_DEPENDENCY`, `THIS_IS_UNDEFINED`]
const dynamicImportWarningIgnoreList = [