Question

From the google analytics tracking code:

var _gaq = _gaq || [];

how does this work?

Is it a conditional variable value assignment?
Is it the same as saying:

if( !(_gaq) ) {_gaq = []; }

?

Answer 1

The or operator (||) will return the left hand side if it is a true value, otherwise it will return the right hand side.

It is very similar to your second example, but since it makes use of the var keyword, it also establishes a local scope for the variable.