setTimeout 与setInterval的区别

setTimeout(code,millisec) 方法用于在指定的毫秒数后调用函数或计算表达式

setInterval(code,millisec) 方法可按照指定的周期（以毫秒计）来调用函数或计算表达式

区别：setTimeout() 只执行 code 一次。如果要多次调用，请使用 setInterval() 或者让 code 自身再次调用 setTimeout()

 

setTimeout() 函数实现时钟的例子

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>预备启动秒表</title>
    <script type="text/javascript">
        function timedMsg()
        {
            var second = document.getElementById("second").value;
            var minute = document.getElementById("minute").value;
            var hour = document.getElementById("hour").value;

            second = parseInt(second);
            minute = parseInt(minute);
            hour = parseInt(hour);

            var second = second + 1;
            if(second >59){
                second = 0;
                minute = minute + 1;
                if(minute > 59){
                    minute = 0;
                    hour = hour + 1;
                    if(hour>23){
                        hour = 0;
                    }
                }
            }
            //数据格式处理
            if(second < 10){
                second = "0" + second;
            }
            if(minute < 10){
                minute = "0" + minute;
            }
            if(hour < 10){
                hour = "0" + hour;
            }

            document.getElementById('second').value= second;
            document.getElementById('minute').value= minute;
            document.getElementById('hour').value= hour;

            var t = setTimeout("timedMsg();",1000);
        }
    </script>
</head>
<body>
    <button onclick="timedMsg()">预备启动秒表</button>
    <br>
    <br>
    时<input type="text" name="hour" id="hour" value="00">
    分<input type="text" name="minute" id="minute" value="00">
    秒<input type="text" name="second" id="second" value="00">
</body>
</html>

 

posted @ 2018-03-16 11:42  坚持奔跑在路上  阅读(209)  评论(0)  编辑  收藏  举报