Function terserPlugin

packages/vite/src/node/plugins/terser.ts:38–139

(config: ResolvedConfig)

}

export function terserPlugin(config: ResolvedConfig): Plugin {
  const { maxWorkers, ...terserOptions } = config.build.terserOptions

  const makeWorker = () =>
    new WorkerWithFallback(
      () =>
        async (
          terserPath: string,
          code: string,
          options: TerserMinifyOptions,
        ) => {
          const terser: typeof import('terser') = await import(terserPath)
          try {
            return (await terser.minify(code, options)) as TerserMinifyOutput
          } catch (e) {
            // convert to a plain object as additional properties of Error instances are not
            // sent back to the main thread
            throw { stack: e.stack /* stack is non-enumerable */, ...e }
          }
        },
      {
        shouldUseFake(_terserPath, _code, options) {
          return !!(
            (typeof options.mangle === 'object' &&
              (options.mangle.nth_identifier?.get ||
                (typeof options.mangle.properties === 'object' &&
                  options.mangle.properties.nth_identifier?.get))) ||
            typeof options.format?.comments === 'function' ||
            typeof options.output?.comments === 'function' ||
            options.nameCache
          )
        },
        max: maxWorkers,
      },
    )

  let worker: ReturnType<typeof makeWorker>

  return {
    name: 'vite:terser',

    applyToEnvironment(environment) {
      // We also need the plugin even if minify isn't 'terser' as we force
      // terser in plugin-legacy
      return !!environment.config.build.minify
    },

    async renderChunk(code, chunk, outputOptions) {
      // This plugin is included for any non-false value of config.build.minify,
      // so that normal chunks can use the preferred minifier, and legacy chunks
      // can use terser.
      if (
        config.build.minify !== 'terser' &&
        !this.environment.config.isOutputOptionsForLegacyChunks?.(outputOptions)
      ) {
        return null
      }