1. 侧边栏广告

1     window.onload = window.onresize = window.onscroll = function() { 2         var oDiv = document.getElementById("div1"); 3 4 //页面滚动的距离 5 var scrollTop = 6 document.documentElement.scrollTop || document.body.scrollTop; 7 8 //DIV顶部距离可见窗口顶部的距离 9 var t = (document.documentElement.clientHeight - oDiv.offsetHeight) / 2; 10 11 //设置广告的位置 12 oDiv.style.top = scrollTop + t + "px"; 13 }

2. 回到顶部

1     window.onload = function() { 2         var oBtn = document.getElementById("btn1"); 3 var timer = null; 4 var isSys = false; 5 6 //如果是用户拖动了滚动条，则停止滑动 7 window.onscroll = function() { 8 if (!isSys) { 9 clearInterval(timer); 10 } 11 isSys = false; 12 }; 13 14 oBtn.onclick = function() { 15 timer = setInterval(function() { 16 isSys = true; 17 18 //页面滚动的距离 19 var scrollTop = 20 document.documentElement.scrollTop || document.body.scrollTop; 21 var iSpeed = Math.floor(-scrollTop / 8); 22 23 //如果到达顶部，则清除定时器 24 if (scrollTop === 0) { 25 clearInterval(timer); 26 } 27 28 document.documentElement.scrollTop = 29 document.body.scrollTop = scrollTop + iSpeed; 30 }, 30); 31 }; 32 };