~~~
<body>
<button id="btn">btn</button>
<button id="clear">清楚定时器</button>
<script>
var timer;
var btn=document.getElementById("btn");
var clear = document.getElementById("clear");
btn.onclick=function(){
timer =setInterval(function(){
alert(1)
},1000)
}
clear .onclick=function(){
clearInterval(timer);
}
</script>
</body>
~~~
