<!DOCTYPE html
>
<html
>
<head
>
<meta charset
="utf-8">
<title
></title
>
<script type
="text/javascript">
var se
;
se
=document
.getElementById("time");
var c
=10;
var t
;
function countDown(){
t
=setInterval(f
,1000);
}
function f(){
se
.innerHTML
=c
;
if(--c
<0){
clearInterval(t
);
}
}
</script
>
</head
>
<body
>
<span id
="time"></span
>
<br
><br
>
<input type
="button" value
="开始倒计时"
onclick
="countDown();" />
</body
>
</html
>
<!DOCTYPE html
>
<html
>
<head
>
<meta charset
="utf-8">
<title
></title
>
<script type
="text/javascript">
var se
;
var c
=10;
var t
;
function countDown(){
t
=setInterval(f
,1000);
}
function f(){
se
=document
.getElementById("time");
se
.innerHTML
=c
;
if(--c
<0){
clearInterval(t
);
}
}
</script
>
</head
>
<body
>
<span id
="time"></span
>
<br
><br
>
<input type
="button" value
="开始倒计时"
onclick
="countDown();" />
</body
>
</html
>
在使用节点的innerHTML时，尤其是结合周期计时器使用时，一定要保证每次赋值时，都要获取到该对象节点
