下面的JS代码点击开始按钮后开始计时，点击停止按钮后停止计时
<!DOCTYPE html>
<html>
<head>
<script>
var c=0;
var t;
var timer_is_on=0;
function timedCount()
{
document.getElementById('txt').value=c;
c=c+1;
t=setTimeout(function(){timedCount()},1000);
}
function doTimer()
{
if (!timer_is_on)
{
timer_is_on=1;
timedCount();
}
}
function stopCount()
{
clearTimeout(t);
timer_is_on=0;
}
</script>
</head>
<body>
<form>
<input type="button" value="Start count!" onclick="doTimer()" />
<input type="text" id="txt" />
<input type="button" value="Stop count!" onclick="stopCount()" />
</form>
<p>
Click on the "Start count!" button above to start the timer. The input field will count forever, starting at 0. Click on the "Stop count!" button to stop the counting. Click on the "Start count!" button to start the timer again.
</p>
</body>
</html>
开心洋葱 , 版权所有丨如未注明 , 均为原创丨未经授权请勿修改 , 转载请注明JavaScript如何使用setTimeout和clearTimeout控制定时器的开关！
