Thread:Talk:JavaScript performance/lorem == null/reply

Can you elaborate on this ?

Although it's not that common, I find it very useful in handling optional arguments (ie. not given (undefined) or null was passed). jQuery uses this a lot internally as well. It's kind of like  in PHP.

Either way, if one is looking specifically for undefined or null, a comparison should always be strictly checking for that. But if both are values that should return true, I don't see why one would want to write two checks that accomplish the same thing.