window.event.target not working

Each row in my table consists of a number of columns. The first column contains a checkbox. I want to display details for the row if any column of the row has been clicked, except the first one. This code works fine in IE, but when I run it in Mozilla, I get "targ has no properties" error. It looks like window.event is not recognized because none of the alerts are displayed. Is it my browser settings?
Thanks.

<tbody onClick='doSelect(this);'>

    var targ;
    if (!e) {
       alert("1");
      var e = window.event;
       }
    if (e.target) {
      alert("2");
      targ = e.target;
    }
    else if (e.srcElement) targ = e.srcElement;
    if (targ.nodeType == 3) // defeat Safari bug
        targ = targ.parentNode;

    if ( targ.tagName == "INPUT" && targ.type == "checkbox" ) {
          return;
    }