定时器定时循环执行和只执行一次

DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Titletitle>
head>
<body>

<input type="text" id="clock" style="width: 249px">
<input type="button" value="begin" onclick="begin_click()">
<input type="button" value="End" onclick="End()">
<input type="button" value="timeout" onclick="f1()">

<script>
    function Timeout() {
        alert(123);
    }
    function f1() {
        var ID=setTimeout(Timeout,1000); //1秒后执行一次,只执行一次
        clearTimeout(ID) //清除定时器
    }


    function begin() {
        var stime=getTime();
        var ret=document.getElementById("clock"); //找到id为"clock"的元素
        ret.value=stime; //给元素赋值
    }

    var ID;
    function begin_click() {
         if (ID==undefined){
              begin();
              ID=setInterval(begin,1000);//开启循环定时器
         }

    }
    function End() {

        clearInterval(ID); //清除定时器
        ID=undefined;
    }
    
   // ---------------------------------定时器-----

    function getTime() {
     var date_obj= new Date();
    var year=date_obj.getFullYear();
    var month=date_obj.getMonth()+1;
    var day=date_obj.getDate();
    var hour=date_obj.getHours();
    var minute=date_obj.getMinutes();
    var seconds=date_obj.getSeconds();
    var week=date_obj.getDay();

    return year+""+month+""+f(day)+""+" "+hour+": "+minute+" :"+seconds+" "+num_week(week)
}
    function f(num) {
        if (num<10){
             return "0"+num;
        }
        return num;
    }
    function num_week(n) {
        week=["星期日","星期一","星期二","星期三","星期四","星期五","星期六"]
        return week[n]
    }

script>
body>
html>

 

转载于:https://www.cnblogs.com/jiefangzhe/p/8149930.html

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