我想在while循环中添加一个delay/sleep:

我是这样试的:

alert('hi');

for(var start = 1; start < 10; start++) {
  setTimeout(function () {
    alert('hello');
  }, 3000);
}

只有第一种情况是正确的:在显示alert('hi')后,它将等待3秒,然后alert('hello')将显示,但随后alert('hello')将不断重复。

我想要的是,在警报('hello')显示3秒后警报('hi'),然后它需要等待3秒的第二次警报('hello'),以此类推。


当前回答

在ES6中,你可以这样做:

对于(设I = 0;I <= 10;我+ +){ setTimeout(函数(){ console.log(我); },我* 3000) }

在ES5中,你可以这样做:

For (var I = 0;I <= 10;我+ +){ (函数(i) { setTimeout(函数(){ console.log(我); },我* 3000) }) (); }

原因是,let允许您声明限制在块语句或使用它的表达式范围内的变量,而不像var关键字那样全局定义变量,或局部定义整个函数,而不考虑块范围。

其他回答

我可能会使用setInterval,像这样:

var period = 1000; // ms
var endTime = 10000;  // ms
var counter = 0;
var sleepyAlert = setInterval(function(){
    alert('Hello');
    if(counter === endTime){
       clearInterval(sleepyAlert);
    }
    counter += period;
}, period);
const autoPlayer = (arr = [1, 2, 3, 4, 5]) => {
  // Base case:
  if (arr.length < 1) return

  // Remove the first element from the array.
  const item = arr.shift()

  // Set timout 
  setTimeout(() => {
    console.log('Hello, world!', item)  // Visualisation.
    autoPlayer() // Call function again.
  }, 1000) // Iterate every second.
}

Hey, I know this post is very old, but this code "loops" and adds a delay to it using a recursive method. I don't think you can 'actually' delay a loop itself from iterating based on reading various comments from other people. Maybe this can help someone out! Basically the function accepts an array (in this example). On each iteration the setTimeout Javascript method is called. The function calls itself again indefinitely when the timer of the setTimeout function expires, but on each call the array becomes smaller until it reaches the base-case. I hope this can help anyone else out.

我用蓝鸟的承诺。延时和递归。

函数 myLoop(i) { 返回承诺延迟(1000) .then(function() { 如果 (i > 0) { 警报(“你好”); 返回 myLoop(i -= 1); } }); } 我的循环(3); <script src=“//cdnjs.cloudflare.com/ajax/libs/bluebird/2.9.4/bluebird.min.js”></script>

如果使用ES6,你可以使用for循环来实现:

For(令I = 1;I < 10;我+ +){ setTimeout(函数定时器(){ console.log(“hello world”); }, I * 3000); }

它为每次迭代声明i,这意味着超时是+ 1000之前的超时。这样,传递给setTimeout的就是我们想要的。

这是可行的

for (var i = 0; i < 10; i++) {
  (function(i) {
    setTimeout(function() { console.log(i); }, 100 * i);
  })(i);
}

试试这把小提琴:https://jsfiddle.net/wgdx8zqq/