zone_async_status.js

let macroTaskCount = 0;
let microTaskCount = 0;
const zone = Zone.current.fork({
  name: 'monitor',
  onScheduleTask: (delegate, curr, target, task) => {
    if (task.type === 'macroTask') {
      macroTaskCount ++;
      log('new macroTask will be scheduled: ' + macroTaskCount);
    } else if (task.type === 'microTask') {
      microTaskCount ++;
      log('new microTask will be scheduled: ' + microTaskCount);
    }
    return delegate.scheduleTask(target, task);
  },
  onInvokeTask: (delegate, curr, target, task, applyThis, applyArgs) => {
    const r = delegate.invokeTask(target, task, applyThis, applyArgs);
     if (task.type === 'macroTask') {
      macroTaskCount --;
      log('macroTask is invoked: ' + macroTaskCount);
    } else if (task.type === 'microTask') {
      microTaskCount --;
      log('microTask is invoked: ' + microTaskCount);
    }
    return r;
  },
});

zone.run(() => {
  for (let i = 0; i < 5; i ++) {
    setTimeout(() => {});
  }
  for (let i = 0; i < 5; i ++) {
    Promise.resolve(1).then(() => {});
  }
});
// macroTask will be scheduled, 1
// macroTask will be scheduled, 2
// macroTask will be scheduled, 3
// macroTask will be scheduled, 4
// macroTask will be scheduled, 5
// microTask will be scheduled, 1
// microTask will be scheduled, 2
// microTask will be scheduled, 3
// microTask will be scheduled, 4
// microTask will be scheduled, 5
// microTask is invoked, 4
// microTask is invoked, 3
// microTask is invoked, 2
// microTask is invoked, 1
// microTask is invoked, 0
// macroTask is invoked, 4
// macroTask is invoked, 3
// macroTask is invoked, 2
// macroTask is invoked, 1
// macroTask is invoked, 0