js定时器

setTimeout(方法名,延迟时间);

<script> 
function hello(){ 
alert("hello"); 
} 
//重复执行某个方法 
var t1 = window.setInterval(hello,1000); 
var t2 = window.setInterval("hello()",3000); 
//去掉定时器的方法 
window.clearInterval(t1); 
</script>