How to use the setTimeout method-JS Tutorial-php.cn

How to use the setTimeout method

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Release： 2019-01-30 16:26:21

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The setTimeout() method will call the function after the time specified in milliseconds. The setTimeout method requires 2 parameters: a reference to the callback function and a delay in milliseconds. In this article, we will take a look at the setTimeout method. specific usage.

How to use the setTimeout method

Let’s first look at the basic syntax of setTimeout

setTimeout(function, milliseconds, param_one, param_two, ...)

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To stop setTimeout and prevent the execution of the function, you need to use the clearTimeout() method.

The setTimeout() method returns an ID that can be used in the clearTimeout() method.

Let’s look at a simple example

The code is as follows

<!DOCTYPE html>
<html>
<body>

<script>
  var sampleVar;
  function sampleFunction(){    
    sampleVar = setTimeout(alertFunc, 2000);
  }
  function alertFunc(){    
    alert("Two seconds have passed!");
  }
  sampleFunction();
</script>

</body>
</html>

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The above code will open the pop-up window after 2 seconds.

Example 2

This example will change the text of the element every 2 seconds (3 times). To do this, the ID of some HTML element must be set to "counter".

The code is as follows

<!DOCTYPE html>
<html>
<body>

<p>单击下面的按钮。输入字段将显示经过2、4和6秒。</p>

<button onclick="timedText()">Display timed text</button>

<input type="text" id="text">

<script>
function timedText() {
    var x = document.getElementById("text");
    setTimeout(function(){ x.value="2 seconds" }, 2000);
    setTimeout(function(){ x.value="4 seconds" }, 4000);
    setTimeout(function(){ x.value="6 seconds" }, 6000);
}
</script>

</body>
</html>

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The display effect on the browser is as follows

How to use the setTimeout method

When you click the button on the left, the process will be displayed in the text box 2, 4, 6 seconds

This sample will stop "timeout" if "samplestopfunction" is called before the timer runs out.

The code is as follows

<!DOCTYPE html>
<html>
<body>

<p>等待3秒钟后，单击第一个按钮显示“Hi”。</p>
<p>单击第二个按钮以阻止执行第一个函数<br>（必须在3秒钟前单击它）</p>

<button onclick="sampleFunction()">Try it</button>
<button onclick="sampleStopFunction()">Stop the alert</button>

<script>
var sampleVar;

function sampleFunction() {
 sampleVar = setTimeout(function(){ alert("Hi") }, 2000);
}

function sampleStopFunction() {
 clearTimeout(sampleVar);
}
</script>

</body>
</html>

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The display effect on the browser is as follows

How to use the setTimeout method

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