browserSniffer.js

function browserSniffer() {
  this.ie4 = document.all && !document.getElementById;
  this.ns4 = document.layers;
  this.ie5 = document.all && document.getElementById;
  this.ns6 = document.getElementById && !document.all;
}

In future versions of DOCJSLIB, we plan to load only the relevant API instead of all four. The file would look like this:

function browserSniffer() {
  this.ie4 = document.all && !document.getElementById;
  this.ns4 = document.layers;
  this.ie5 = document.all && document.getElementById;
  this.ns6 = document.getElementById && !document.all;
  if (this.ie4) document.write('<SCRIPT LANGUAGE="JavaScript" 
                                 SRC="docjslibIE4SubClass.js"></SCRIPT>')
  else if (this.ie5) document.write('<SCRIPT LANGUAGE="JavaScript" 
                                 SRC="docjslibIE5SubClass.js"></SCRIPT>')
  else if (this.ns4) document.write('<SCRIPT LANGUAGE="JavaScript" 
                                 SRC="docjslibNS4SubClass.js"></SCRIPT>')
  else if (this.ns6) document.write('<SCRIPT LANGUAGE="JavaScript" 
                                 SRC="docjslibNS6SubClass.js"></SCRIPT>')			 
}

Next: Creating a browser-dependent subclass on the fly