[RxJS] Extend Promises by Adding Custom Behavior

We will create a Promise wrapper, that can be used instead of normal promises, to track different tasks that we need to show the spinner for.

export class PromiseWithLoadingProgress extends Promise {
  constructor(callback) {
    super((originalResolve, originalReject) => {
      const resolveSpy = (...args) => {
        originalResolve(...args);
        existingTaskCompleted();
      };
      const rejectSpy = (...args) => {
        originalReject(...args);
        existingTaskCompleted();
      };
      callback(resolveSpy, rejectSpy);
    });
    newTaskStarted();
  }
}

const doVeryQuickWork = () => {
  new PromiseWithLoadingProgress(resolve => {
    setTimeout(() => {
      resolve();
    }, 300);
  });
};

const doAlmostQuickWork = () => {
  new PromiseWithLoadingProgress(resolve => {
    setTimeout(() => {
      resolve();
    }, 2200);
  });
};