Detecting a layer by name

Question

The following code is part of a larger script. I'm trying to detect if the layer "Canons Grid" exists. If it doesn't then create a new layer with that name. This code fails everytime, even if the layer doesn't exist. What am i doing wrong?
var doc = app.activeDocument;
var canonLayer;     
      try {
                  canonLayer = doc.layers.itemByName("Canons Grid");
            catch(e)
                  canonLayer = doc.layers.add({name: "Canons Grid"});

Answer 1

canonLayer = doc.layers.itemByName("Canons Grid");
always succeeds, as your own code demonstrates:
var canonLayer = doc.layers.item("Canons");
if (canonLayer.isValid == false) {
Therefore in tusharde's original code, the catch() never executes.
Peter