// JavaScript Document (function() { var doc = document, side = (function() { var body = doc.body, firstChild = body.firstChild, wrap = doc.createElement('div'); wrap.className = 'side-btns-wrap'; wrap.innerHTML = '<div id="backtop" style="bottom: 300px;"></div>'; firstChild ? firstChild.parentNode.insertBefore(wrap, firstChild) : body.appendChild(wrap); return wrap; })(), addEvent = function(o, s, fn) { if (o.attachEvent) { o.attachEvent('on' + s, fn); } else { o.addEventListener(s, fn, false); } return o; }, toggle = function() { var top = doc.documentElement.scrollTop || doc.body.scrollTop, visible = (top > 0 ? 'visible' : 'hidden'); side.style.visibility = visible; }, toTop = function() { doc.documentElement.scrollTop = 0; doc.body.scrollTop = 0; }; addEvent(window, 'scroll', toggle); addEvent(side, 'click', toTop); })();
CSS代码：#backtop:hover { background:#09F url(Totophover.png) center no-repeat; opacity: 1; } #backtop { opacity: 0.6; } #backtop { border-radius:50%; width: 68px; height: 69px; background:#9ca5b2 url(Totop.png) center no-repeat; display: block; position: fixed; right: 10px; bottom: -40px; cursor: pointer; z-index: 99; margin-left: -40px; }使用试，在网站底部加入JS调用即可。
