计数器
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>计数器</title>
</head>
<body>
<input type="button" value="开始计数" onclick="startCount()">
<input id="num" type="text">
<input type="button" value="停止计数" onclick="stopCount()">
<script>
var timer = null, c = 0;
function timedCount() { // 在文本框中显示数据
document.getElementById('num').value = c;
++c; // 显示数据加1
}
function startCount() { // 开始间歇调用
timer = setInterval(timedCount, 1000);
}
function stopCount() { // 清除间歇调用
clearInterval(timer);
}
</script>
</body>
</html>
