remove blank entries from array

[jackvull]

I have some code that fills drop downs based on the drop down before it:

function fillBusUnitLevels () {
//alert(document.getElementById("DivisionalLevels").value);
//clear list
document.getElementById("BusUnitLevels").options.length = 0;
//reset
var optn = document.createElement("OPTION");
optn.text = "--- Choose data ---";
optn.value = "default";
document.getElementById("BusUnitLevels").options.add(optn);
var optn = document.createElement("OPTION");
optn.text = "All Business Unit Levels";
optn.value = "All";
document.getElementById("BusUnitLevels").options.add(optn);
document.getElementById("RegionalLevels").disabled=true;
document.getElementById("CostCentreLevels").disabled=true;
//create copy of the array to work with
var workingstructure = new Array();
var arrDD = new Array();
for (i = 0; i < structure.length; i++) {
workingstructure[i] = structure[i][3];
}
arrDD = unique(workingstructure,false);
arrDD.sort();
//fill
if (document.getElementById("DivisionalLevels").value == "All") {
for (i = 0; i < arrDD.length; i++) {
var optn = document.createElement("OPTION");
optn.text = arrDD[i];
optn.value = arrDD[i];
document.getElementById("BusUnitLevels").options.add(optn);
}
}
else if (document.getElementById("DivisionalLevels").value.substring(0,2) == "SY") {
for (i = 0; i < arrDD.length; i++) {
var optn = document.createElement("OPTION");
optn.text = arrDD[i];
optn.value = arrDD[i];
if (document.getElementById("DivisionalLevels").value.substring(0,3) == optn.text.substring(0,3)) {
document.getElementById("BusUnitLevels").options.add(optn);
}
}
}
//destroy the array
workingstructure = null;
arrDD = null;
}

I changed one of the the above sections to the following but now the drop down doesn't display anything. Any ideas why?
I'm trying to ignore blank entries in the array...

for (i = 0; i < structure.length; i++) {
if (structure[i][3] == "") { //ignores the elements in the structure that don't have a node
workingstructure[i] = structure[i][3];
}
}

[Wolf_man]

I may not be reading this correctly but I think you may want to change

== to !=

because, you want to add the structure only if it is not blank.