1，
var myVar = setInterval(function(){ myTimer() }, 1000);
function myTimer() {
var d = new Date();
var t = d.toLocaleTimeString();
document.getElementById("demo").innerHTML = t;
}
function myStopFunction() {
clearInterval(myVar);
}
https://www.runoob.com/jsref/met-win-clearinterval.html
原文：https://www.cnblogs.com/yang101/p/11621048.html