<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>计时器</title>
</head>
<script type="text/javascript">
var num=0;
function startCount() {
document.getElementById('count').value=num;
num=num+1;
setTimeout("startCount()",1000);
}
startCount();
</script>
</head>
<body>
<form>
<input type="text" id="count" />
</form>
</body>
</html>
2015-04-24
页面元素还没加载 你就调用方法了···这样获取不到对应的元素
两个解决方法
1在外面加个方法 window.onload
window.onload = function(){
var num=0;
function startCount() {
document.getElementById('aa').value=num;
num=num+1;
setTimeout(startCount,1000);
}
startCount();
}2 把js代码放到form 后面
<body>
<form>
<input type="text" id="aa" />
</form>
<script type="text/javascript">
var num=0;
function startCount() {
document.getElementById('aa').value=num;
num=num+1;
setTimeout(startCount,1000);
}
startCount();
</script>
</body>举报
