<!DOCTYPE?HTML>
<html>
<head>
<meta?http-equiv="Content-Type"?content="text/html;?charset=utf-8">
<title>計時器</title>
<script?type="text/javascript">
var?num?=?1;
var?i;
function?startCount()?{
document.getElementById('count').value?=?num;
num?=?num?+?1;
i?=?setTimeout("startCount()",?1000);
console.log("1號:"+num);
}
var?flag?=?0;
function?controlStart()?{
if?(flag?==?0)?{flag?=?1;
num--;startCount();
}
else?{?}
}
function?stopCount()?{
clearTimeout(i);
flag?=?0;
}
function?clear(){
if?(flag?==0){
num?=?0;
document.getElementById("count").value?=?num?;
}
else?{}
}
</script>
</head>
<body>
<form>
<input?type="text"?id="count"?/>
<input?type="button"?value="Start"?onclick="controlStart()"?/>
<input?type="button"?value="Stop"?onclick="stopCount()"?/>
<input?type="button"?value="clear"?onclick="clear()"?/>
</form>
</body>
</html>
為什么num無法清零？代碼如上面，clear（）函數(shù)里面設(shè)置了num=0，但是仍然無法清零。
2018-12-17
給num重新賦值就好了
2018-08-05
看代碼！
2018-07-23