Things will be explained by examples, since this gist is primarily for myself :P
JavaScript short circuits Comparison Operators. Hence, you may be able to gain performance (?) by using them with this in mind.
If variable a has 70% chance of being truthy and variable b has 50% chance of being truthy,
you might prefer to write your if statement as if (b && a) {...} than if (a && b) {...}.
Why? Because with the first, 50% of the time the engine will not even have to check for a's value