下拉菜单网页特效，效果很不错而且符合Web标准

作者：Eve Cole 更新时间：2009-06-20 15:53:55

1.首先在<head>和</head>之间插入下列代码 <style type="text/css"> #floater { position: absolute; left: 500; top: 146; width: 176; visibility: visible; z-index: 10; } --> </style> 2.在body中的任意位置插入下列代码 <div ID="floater" style="left: 590px; top: 158px"> <img src="/img/200406301.jpg" width="127" height="150"> 欢迎光临 </div><script LANGUAGE="JavaScript"> self.onError=null; currentX = currentY = 0; whichIt = null; lastScrollX = 0; lastScrollY = 0; NS = (document.layers) ? 1 : 0; IE = (document.all) ? 1: 0;  function heartBeat() { if(IE) { diffY = document.body.scrollTop; diffX = document.body.scrollLeft; } if(NS) { diffY = self.pageYOffset; diffX = self.pageXOffset; } if(diffY != lastScrollY) { percent = .1 * (diffY - lastScrollY); if(percent > 0) percent = Math.ceil(percent); else percent = Math.floor(percent); if(IE) document.all.floater.style.pixelTop += percent; if(NS) document.floater.top += percent; lastScrollY = lastScrollY + percent; } if(diffX != lastScrollX) { percent = .1 * (diffX - lastScrollX); if(percent > 0) percent = Math.ceil(percent); else percent = Math.floor(percent); if(IE) document.all.floater.style.pixelLeft += percent; if(NS) document.floater.left += percent; lastScrollX = lastScrollX + percent; } }   function checkFocus(x,y) { stalkerx = document.floater.pageX; stalkery = document.floater.pageY; stalkerwidth = document.floater.clip.width; stalkerheight = document.floater.clip.height; if( (x > stalkerx && x < (stalkerx+stalkerwidth)) && (y > stalkery && y < (stalkery+stalkerheight))) return true; else return false; } function grabIt(e) { if(IE) { whichIt = event.srcElement; while (whichIt.id.indexOf("floater") == -1) { whichIt = whichIt.parentElement; if (whichIt == null) { return true; } } whichIt.style.pixelLeft = whichIt.offsetLeft; whichIt.style.pixelTop = whichIt.offsetTop; currentX = (event.clientX + document.body.scrollLeft); currentY = (event.clientY + document.body.scrollTop); } else { window.captureEvents(Event.MOUSEMOVE); if(checkFocus (e.pageX,e.pageY)) { whichIt = document.floater; StalkerTouchedX = e.pageX-document.floater.pageX; StalkerTouchedY = e.pageY-document.floater.pageY; } } return true; } function moveIt(e) { if (whichIt == null) { return false; } if(IE) { newX = (event.clientX + document.body.scrollLeft); newY = (event.clientY + document.body.scrollTop); distanceX = (newX - currentX); distanceY = (newY - currentY); currentX = newX; currentY = newY; whichIt.style.pixelLeft += distanceX; whichIt.style.pixelTop += distanceY; if(whichIt.style.pixelTop < document.body.scrollTop) whichIt.style.pixelTop = document.body.scrollTop; if(whichIt.style.pixelLeft < document.body.scrollLeft) whichIt.style.pixelLeft = document.body.scrollLeft; if(whichIt.style.pixelLeft > document.body.offsetWidth - document.body.scrollLeft - whichIt.style.pixelWidth - 20) whichIt.style.pixelLeft = document.body.offsetWidth - whichIt.style.pixelWidth - 20; if(whichIt.style.pixelTop > document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5) whichIt.style.pixelTop = document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5; event.returnValue = false; } else { whichIt.moveTo(e.pageX-StalkerTouchedX,e.pageY-StalkerTouchedY); if(whichIt.left < 0+self.pageXOffset) whichIt.left = 0+self.pageXOffset; if(whichIt.top < 0+self.pageYOffset) whichIt.top = 0+self.pageYOffset; if( (whichIt.left + whichIt.clip.width) >= (window.innerWidth+self.pageXOffset-17)) whichIt.left = ((window.innerWidth+self.pageXOffset)-whichIt.clip.width)-17; if( (whichIt.top + whichIt.clip.height) >= (window.innerHeight+self.pageYOffset-17)) whichIt.top = ((window.innerHeight+self.pageYOffset)-whichIt.clip.height)-17; return false; } return false; } function dropIt() { whichIt = null; if(NS) window.releaseEvents (Event.MOUSEMOVE); return true; }  if(NS) { window.captureEvents(Event.MOUSEUP|Event.MOUSEDOWN); window.onmousedown = grabIt; window.onmousemove = moveIt; window.onmouseup = dropIt; } if(IE) { document.onmousedown = grabIt; document.onmousemove = moveIt; document.onmouseup = dropIt; } if(NS || IE) action = window.setInterval("heartBeat()",1); </script> //转载请注明出处:建站学院。