怎样问题在水平和垂直滚动后总保持div的位置在屏幕看得见的最左边和中间（因为有时滚动不一定是滚动到最左边）

参见
http://dotnet.aspx.cc/右下角的例子
<html>
<head>
<title>圖書管理系統[圖書資料]</title>
<meta http-equiv="Content-Type" content="text/html; charset=big5">
<STYLE>
.{font:10pt 宋体;color:#191970;}
th{background-color:#7171C6;color:#ffffff;}
input{color:#FF0066;font:8pt}
option{color:#0000ff;}
</STYLE>
<style type="text/css">
#floater {
    position: absolute;
    left: 500;
    top: 70;
    width: 125;
    visibility: visible;
    z-index: 10;
}
-->
</style>
<script LANGUAGE="JAVASCRIPT">
function resetLocation(){
var eDiv=document.all('floater');
eDiv.style.pixelTop=(document.body.offsetHeight - eDiv.offsetHeight)/2;
eDiv.style.pixelLeft=(document.body.offsetWidth - eDiv.offsetWidth)/2;
}
</SCRIPT>
</head><body bgcolor="#FFFFFF" text="#000000" onload="resetLocation()">
<div ID="floater">
<p align="center" style="color:#0000ff">請選擇圖書類別
<select name="select1">
  <option value="WEB" selected>WEB類</option>
  <option value="ORA">ORACLE類</option>
  <option value="NET">網絡類</option>
  <option value="PB">Power Builder類</option>
  <option value="VB">Visual Basic類</option>
  <option value="SA">SQL&Access類</option>
  <option value="HP">HP類</option>
  <option value="CD">光盤類</option>
  <option value="OTH">其它類</option>
  <option value="SYS">作業系統類</option>
</select></P>
</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><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
<p style="width:2000px;">a</p>
</body>
</html>
利用offsetLeft 来实现就可以了。。。

调试易

怎样问题在水平和垂直滚动后总保持div的位置在屏幕看得见的最左边和中间（因为有时滚动不一定是滚动到最左边）

解决方案 »