計(jì)時(shí)器setTimeout()
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>計(jì)時(shí)器</title>
</head>
<script type="text/javascript">
? var num=0;
? function startCount() {
? ? document.getElementById('count').value=num;
? ? num=num+1;
? ? setTimeout("startCount()",1000);
? }
? setTimeout("startCount()",1000);
</script>
</head>
<body>
<form>
<input type="text" id="count" />
</form>
</body>
為什么num=num++不可以執(zhí)行？
2016-03-03
num=++num就可以，因?yàn)閚um++是先賦值再自加，所以一直是0