A little JS class to help with running functions in web workers.

WorkerScope.js

/**
 * WorkerScope prepares a function to be run in a web worker
 * without needing an external JavaScript file or forcing you
 * to deal with event listener.
 * 
 * Example usage:
 *
 *     await result = new WorkerScope(
 *        () => self.postMessage('hi!')
 *     ).run() // 'hi'
 */
class WorkerScope {
  /**
   * @param {Function} fun  The function to run in a worker.
   * @param {Object}   args The args to start the worker with.
   */
  constructor(fun, args = 0) {
    this.fun = fun;
    this.args = args;
  }

  /**
   * Returns a pending promise with the result of the worker task.
   */
  run() {
    return new Promise(resolve => {
      // Construct the web worker.
      const blob = new Blob(
        [`onmessage=${this.fun}`],
        { type: 'application/javascript' }
      );
      const blobURL = URL.createObjectURL(blob);
      const worker = new Worker(blobURL);
      URL.revokeObjectURL(blobURL);

      worker.onmessage = function (e) {
        return resolve(e.data);
      };
      // Start the worker.
      worker.postMessage(this.args)
    });
  }
}