JavaScript instance parsing clear timer

This article brings you relevant knowledge about javascript, which mainly introduces issues related to timers and clearing timers. You can use the clearTimeout method and clearInterval method to clear the specified timer. Device, let’s take a look at it together, I hope it will be helpful to everyone.

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setTimeout timer

window.setTimeout(call function, delay time);

• This window can omit this delay when calling

• ## The time unit is milliseconds but can be omitted. If omitted, the default is 0

• This calling function can directly write the function or write the function name

• There may be many timers in the page. We often add the identifier

         setTimeout(function(){
            console.log('你好');
         },2000);//2秒后才在控制台输出  你好

setInterval timer

window to the timer. setInterval(calling function, delay time);

• window can be omitted

• This calling function can write the function directly, or write the function name or It takes three forms of string 'function name 0'.

• The number of milliseconds in the interval is omitted and the default is О. If written, it must be milliseconds, indicating how many milliseconds this function is automatically called.

• Because there may be many timers, we often assign an identifier to the timer.

        setInterval(function(){
            console.log('你好');
        },2000)//每隔2秒在控制台输出一次你好，不清除定时器会一直运行

clearTimeout clear timer

It can be seen from the words that clearTimeout is used to clear the first timer;

You need to give a name to the timer that needs to be cleared;

Syntax: clearTimeout (name of timer)

        var timer = setTimeout(function() {
            console.log('你好!');
        },5000);
        clearTimeout(timer);//上面一个定时器就不会在执行程序

clearInterval clear timer

Follow The same as the above timer, it is used to clear the setInterval timer.

You also need to give the timer a name.

Syntax: clearInterval (timer name)

        var times = setInterval(function(){
            console.log('你好!');
        },1000);
        setTimeout(function(){
            clearInterval(times); //5秒后清除定时器
        },5000);

Examples are as follows:

We sometimes write multiple timers and create the timers without saving them in variables. At this time, we cannot clear them directly. Then we can write a method to clear all timers in the page

To clear the timer, you must first understand what the return value is

Understand that the return value of setInterval is a numerical value representing a timer, and this value increases from 1 in the order in which the timer is created. After knowing this order, we clear all timers in the page. It is not difficult to realize the needs

Create a timer directly and then delete it one by one

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javascript video tutorial, web front end】

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