Looping over all window [global] variables in javascript. IE compatible?

Question

I'm trying to loop over all JavaScript variables to find ones that match a certain regex. The function works fine in every browser but IE, it appears that the for loop does not read in every global variable even though it's there. I can access the variable directly using window.variable but it does not appear in the loop.

  var w = window;
  var meta = '';
  var reg = /meta_(.+)/;
  var reg_r;

  for (var k in w){
    if (reg_r = reg.exec(k)){
        if (typeof(w[k])!="undefined" && typeof(reg_r[1])!="undefined"){
            meta +=  reg_r[1] + '=' + escape(w[k]) + '&';
        }
    }
  }

Answer 1

You can't iterate the global context in IE. You just can't. It's an old bug.