<script type="text/javascript">
//定时执行的函数
function demo(){
console.log("demo");
}
//定义定时器(调用函数不加()),此代码执行之后,定时器已启动
var demo_interval = setInterval(demo, 1000);
//停止
clearInterval(demo_interval);
//再次启动
demo_interval = setInterval(demo, 1000);
</script>
