简单问题散分：怎样在netscape 浏览器中得到DIV对象

Question

<layer name=atao></layer>
用document.layers["atao"]或document.layers[0]

Answer 1

function lib_bwcheck(){ //为了提高适用性，必须的除非你打算在一种浏览器中浏览
this.ver=navigator.appVersion; 
this.agent=navigator.userAgent
this.dom=document.getElementById?1:0
this.win = (navigator.appVersion.indexOf("Win")>0);
    this.xwin = (navigator.appVersion.indexOf("X11")>0);
this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom)?1:0;
this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom)?1:0;
this.ie4=(document.all && !this.dom)?1:0;
this.ie=this.ie4||this.ie5||this.ie6
this.mac=this.agent.indexOf("Mac")>-1
this.opera5=this.agent.indexOf("Opera 5")>-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 || this.dom||false);
    this.width = null;
    this.height = null;
return this
}
var bw = new lib_bwcheck();
if(bw.ns4)obj=document.layers[idStr];
else if (bw.ns6) obj= document.getElementById(idStr);
else obj= eval('document.all.'+idStr);ns6不支持document.layers["atao"]
ns4支持document.layers["atao"];
尽量多用this，它是个好东西，和self一样的好用，

Answer 2

在NS6.0里面，我用了var obj = document.getElementById(idStr) ,
但是得到的obj是null，这是怎么回事啊？