besides being really insane typing wise, javascript also both really lenient and unpredictable in what it accepts as expressions. Try to guess the result of the following expressions:

    > [] + []
    >
    > {} + []
    >
    > [] + {}
    >
    > {} + {}

It means that if you feed it nonsense it does not stop you but happily carries on and explodes a few milliseconds later somewhere else. Another can of worms is the difference between null, 0,undefined, '', ....

Ok, you got me worked up. I need to go for a run to blow off steam.