【JavaScript】计时器

<script type="text/javascript">
        onload = function () {
            var p = this.document.getElementById("p");//返回所有的p元素
            this.setInterval(function () {
                var txt = p.innerHTML;
                var head = txt.charAt(0);
                var body = txt.substr(1);

                p.innerHTML = body + head;
            }, 200);//定义计时器
                
                
        }
    </script>

 <script type="text/javascript">
        onload = function () {
           var span = document.getElementById("second");
           var intervalId=setInterval(function () {
                var num = span.innerHTML - 1;

                span.innerHTML = num;

                if (num<=0) {
                    //跳转
                    //停下计时器
                    clearInterval(intervalId);
                    location.href = "http://baidu.com.cn";
                }
            },1000)
        }
    </script>