ExtJS is missing a logging library. What I want is something similar to that of Log4Perl/Log4J.

In the mean time, adding console.log works well, but if you leave it in, you will break your pages for those without Firebug installed (See Internet Explorer).

Here is a quick fix taken from: http://www.id-snippet.com/5402/consolelog-when-firebug-exists-or-not/

(function(__global){
  if (!__global.console || (__global.console && !__global.console.log)) {
    __global.console = {
      log: (__global.opera && __global.opera.postError)
        ? __global.opera.postError
        : function(){ }
    }
  }
})(this);

What would a Log4Ext do

All you have to do is ask the right question, and then search for the answer:

http://log4javascript.org/

It is already written and does what I want :-)