[RESOLVED] Associative array problem, what if item is missing?

[wbport]

I have the following function in various related pages:

function getNoteLength(notelet) {  // Returns duration of note , whole = 768
var NoteLengths = { "16th":48, "32nd":24, "4th":192, "64th":12, "8th":96, "Half":384, "Whole":768, "undefined":-1 }

parts = notelet.split(",");
var  noteLength= -1;
noteLength = NoteLengths[parts[0]];

  for (var i = 1; i < parts.length; i++) {
    if (parts[i].substr(0,9) == "DblDotted") {
	  noteLength = noteLength * 7 / 4; }
	else
      if (parts[i].substr(0,6) == "Dotted") {
	    noteLength = noteLength * 3 / 2; }
	  else
	    if (parts[i].substr(0,7) == "Triplet") {
	      noteLength = noteLength * 2 / 3; } }
  return noteLength;
}

This is my first attempt at using associative arrays (I had been using a traditional search), but was wondering how to I test for a not found condition such as looking for "128th" or "4nd". I would like to return -1, but noteLength comes back as "undefined". The function receives a string such as "4th,Dotted,Slur" for example and would return 288.

TIA