直接使用startCount();
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>计时器</title>
<script type="text/javascript">
var num=0;
function startCount() {
document.getElementById('count').value=num;
num=num+1;
setTimeout("startCount()", 1000);
}
/*
*startCount();
*为什么不可以直接写startCount()这个function,而是要写setTimeout("startCount()",1000)?
*chrome的控制台下报错：
*Uncaught TypeError: Cannot set property 'value' of null
*at startCount (new_file.html?__hbt=1521883370139:9)
*at new_file.html?__hbt=1521883370139:15
*/
setTimeout("startCount", 1000);
</script>
</head>
<body>
<form>
<input type="text" id="count" />
</form>
</body>
</html>
K8sCat浏览 1396回答 1
1回答
-
CodeManDSH
你做的是“计时器”，所以用setTimeout()，一秒后执行一次啊另外最后的：setTimeout("startCount", 1000);应该是：setTimeout("startCount()", 1000);
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相关分类
JavaScript