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Equality (==) - Simple, Right?

Posted January 22, 2009 by senocular

I thought so too. But looking at the docs for the equality (==) operator showed something different. There are literally 15 different bullet points outlining the behavior of this thing! Granted, most of them are pretty obvious, but one I can say I think I would have gotten wrong on the test would be for NameSpace objects.
Apparently Namespace objects are equal simply if their URIs match - this regardless of their prefix values. What that means is:
var ns1:Namespace = new Namespace("foo", "uri");
var ns2:Namespace = new Namespace("bar", "uri");
namespace ns3 = "uri";

trace(ns1 == ns2); // true
trace(ns1 == ns3) // true

If you think about it, it makes sense, but to me, it's not very intuitive, especially when defined through the Namespace class.

Here's another shocker I don't think I've had the pleasure of running into before:
trace(new XMLList() == undefined); // true

Again, thinking about it, you'll want this to be true. But to look at the code above, it's not one's instincts to think it's correct.