js实现0ms延时定时器的几种方式

(function() {
 var timeouts = [];
 var messageName = "zero-timeout-message";
 // Like setTimeout, but only takes a function argument.  There's
 // no time argument (always zero) and no arguments (you have to use a closure)
 function setZeroTimeout(fn) {
  timeouts.push(fn);
  window.postMessage(messageName, "*");
 }
 function handleMessage(event) {
  if (event.source == window && event.data == messageName) {
   event.stopPropagation();
   if (timeouts.length > 0) {
    var fn = timeouts.shift();
    fn();
   }
  }
 }

 window.addEventListener("message", handleMessage, true);

 // Add the one thing we want added to the window object.
 window.setZeroTimeout = setZeroTimeout;
})();

(function() {
 let i = 0;
 const start = Date.now();
 function test() {
  if(i++ < 100) {
   setTimeout(test);
  } else {
   console.log('setTimeout执行时间:', Date.now() - start);
  }
 }
 setTimeout(test);
})();

(function() {
 function setZeroTimeout(fn) {
  queueMicrotask(fn);
 }
 let i = 0;
 const start = Date.now();
 function test() {
  if(i++ < 100) {
   setZeroTimeout(test);
  } else {
   console.log('setZeroTimeout执行时间:', Date.now() - start);
  }
 }
 setZeroTimeout(test);
})();

(function() {
 async function setAsyncTimeout(fn) {
  Promise.resolve().then(fn);
 }
 let i = 0;
 const start = Date.now();
 async function test() {
  if (i++ < 100) {
   await setAsyncTimeout(test);
  } else {
   console.log('setAsyncTimeout执行时间:', Date.now() - start);
  }
 }
 setAsyncTimeout(test);
})();

(function() {
 const channel = new MessageChannel();
 function setMessageChannelTimeout(fn) {
  channel.port2.postMessage(null);
 }
 channel.port1.onmessage = function() {
    test();
 };
 let i = 0;
 const start = Date.now();
 function test() {
  if(i++ < 100) {
   setMessageChannelTimeout(test);
  } else {
   console.log('setMessageChannelTimeout执行时间:', Date.now() - start);
  }
 }
 setMessageChannelTimeout(test);
})();