Question

This only happens on selected sites. I have a bookmarklet. I go to open a box when the user clicks and get this error:

It would seem that the a.wrap part of the expression would guard against undefined.

Answer 1

Well this is pretty simple: the statement is an and and it should be an or.

Update: ok, turns out this is what worked:

    if( a.wrap !=null && typeof a.wrap != "undefined" && typeof a.wrap.unbind != "undefined") {
            a.wrap.unbind(".fb");
      }

instead of:

    unbindEvents : function() {
        a.wrap && a.wrap.unbind(".fb");

Per this link: 30% of defects are logic errors.