判断用户使用的浏览器是否对系统合适的脚本代码

  <script language="JavaScript" type="text/javascript">

function lib_bwcheck(){ //Browsercheck (needed)
 this.ver=navigator.appVersion
 this.agent=navigator.userAgent
 this.dom=document.getElementById?1:0
 this.opera5=this.agent.indexOf("Opera 5")>-1
 this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom && !this.opera5)?1:0;
 this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom && !this.opera5)?1:0;
 this.ie4=(document.all && !this.dom && !this.opera5)?1:0;
 this.ie=this.ie4||this.ie5||this.ie6
 this.mac=this.agent.indexOf("Mac")>-1
 this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0;
 this.ns4=(document.layers && !this.dom)?1:0;
 this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera5)
 return this
}
var bw=new lib_bwcheck()
sLeft =15  //The left placement of the menu
sTop = 44     //The top placement of the menu
sMenuheight = 30  //The height of the menu
sArrowwidth = 11  //Width of the arrows
sScrollspeed = 20 //Scroll speed: (in milliseconds, change this one and the next variable to change the speed)
sScrollPx = 8     //Pixels to scroll per timeout.
sScrollExtra = 15 //Extra speed to scroll onmousedown (pixels)

/**************************************************************************
Scrolling functions
***************************************************************************/
var tim = 0
var noScroll = true
function mLeft(){
 if (!noScroll && oMenu.x<sArrowwidth){
  oMenu.moveBy(sScrollPx,0)
  tim = setTimeout("mLeft()",sScrollspeed)
 }
}
function mRight(){
 if (!noScroll && oMenu.x>-(oMenu.scrollWidth-(pageWidth))-sArrowwidth){
  oMenu.moveBy(-sScrollPx,0)
  tim = setTimeout("mRight()",sScrollspeed)
 }
}
function noMove(){
 clearTimeout(tim);
 noScroll = true;
 sScrollPx = sScrollPxOriginal;
}
/**************************************************************************
Object part
***************************************************************************/
function makeObj(obj,nest,menu){
 nest = (!nest) ? "":'document.'+nest+'.';
 this.elm = bw.ns4?eval(nest+"document.layers." +obj):bw.ie4?document.all[obj]:document.getElementById(obj);
    this.css = bw.ns4?this.elm:this.elm.style;
 this.scrollWidth = bw.ns4?this.css.document.width:this.elm.offsetWidth;
 this.x = bw.ns4?this.css.left:this.elm.offsetLeft;
 this.y = bw.ns4?this.css.top:this.elm.offsetTop;
 this.moveBy = b_moveBy;
 this.moveIt = b_moveIt;
 this.clipTo = b_clipTo;
 return this;
}
var px = bw.ns4||window.opera?"":"px";
function b_moveIt(x,y){
 if (x!=null){this.x=x; this.css.left=this.x+px;}
 if (y!=null){this.y=y; this.css.top=this.y+px;}
}
function b_moveBy(x,y){this.x=this.x+x; this.y=this.y+y; this.css.left=this.x+px; this.css.top=this.y+px;}
function b_clipTo(t,r,b,l){
 if(bw.ns4){this.css.clip.top=t; this.css.clip.right=r; this.css.clip.bottom=b; this.css.clip.left=l;}
 else this.css.clip="rect("+t+"px "+r+"px "+b+"px "+l+"px)";
}
/**************************************************************************
Object part end
***************************************************************************/

/**************************************************************************
Init function. Set the placements of the objects here.
***************************************************************************/
var sScrollPxOriginal = sScrollPx;
function sideInit(){
 //Width of the menu, Currently set to the width of the document.
 //If you want the menu to be 500px wide for instance, just
 //set the pageWidth=500 in stead.
 pageWidth = (bw.ns4 || bw.ns6 || window.opera)?innerWidth:((document.body.clientWidth)-45);

 //Making the objects...
 oBg = new makeObj('divBg')
 oMenu = new makeObj('divMenu','divBg',1)
 oArrowRight = new makeObj('divArrowRight','divBg')

 //Placing the menucontainer, the layer with links, and the right arrow.
 oBg.moveIt(sLeft,sTop) //Main div, holds all the other divs.
 oMenu.moveIt(sArrowwidth,null)
 oArrowRight.css.width = sArrowwidth;
 oArrowRight.moveIt(pageWidth-sArrowwidth,null)

 //Setting the width and the visible area of the links.
 if (!bw.ns4) oBg.css.overflow = "hidden";
 if (bw.ns6) oMenu.css.position = "relative";
 oBg.css.width = pageWidth+px;
 oBg.clipTo(0,pageWidth,sMenuheight,0)
 oBg.css.visibility = "visible";
}

//executing the init function on pageload if the browser is ok.
if (bw.bw) onload = sideInit;
</script>