Javascript 1 Liner Question [duplicate]

Question

Possible Duplicate:
What does “options = options || {}” mean in Javascript?

What does the following line of Javascript code do?

var somevar = window.somevar || {};

Answer 1

It sets somevar to window.somevar if window.somevar exists and is not boolean false, otherwise it sets it to an empty object {}

It's a common idiom for handling variables which may not have been set.