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

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.

其他回答

下面是我如何创建一个无限循环的延迟,在特定条件下中断:

  // Now continuously check the app status until it's completed, 
  // failed or times out. The isFinished() will throw exception if
  // there is a failure.
  while (true) {
    let status = await this.api.getStatus(appId);
    if (isFinished(status)) {
      break;
    } else {
      // Delay before running the next loop iteration:
      await new Promise(resolve => setTimeout(resolve, 3000));
    }
  }

这里的关键是创建一个通过超时解析的新Promise,并等待它的解析。

显然你需要async/await支持。工作在Node 8。

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/

试试这样做:

var i = 0, howManyTimes = 10; 函数f() { console.log(“嗨”); 我+ +; if (i < howManyTimes) { setTimeout (3000); } } f ();

setTimeout()函数是非阻塞的,将立即返回。因此,您的循环将非常快速地迭代,它将快速连续地启动一个接一个的3秒超时触发器。这就是为什么你的第一个警告会在3秒后弹出,而所有其他的警告都会紧随其后,没有任何延迟。

你可能想用这样的东西代替:

var i = 1; // set your counter to 1 function myLoop() { // create a loop function setTimeout(function() { // call a 3s setTimeout when the loop is called console.log('hello'); // your code here i++; // increment the counter if (i < 10) { // if the counter < 10, call the loop function myLoop(); // .. again which will trigger another } // .. setTimeout() }, 3000) } myLoop(); // start the loop

你也可以通过使用一个自调用函数,将迭代次数作为参数传递给它:

(函数myLoop(i) { setTimeout(函数(){ console.log('你好');//你的代码 if(——i) myLoop(i);//减少i,如果i > 0再次调用myLoop }, 3000) }) (10);//传递迭代次数作为参数

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。