Accessing a number using the array operator e.g. 1[0] returns undefined

[cmdcolin]

I stumbled on this one today. we had some type confusion and i was accessing a number with a array operator. I am not sure why this returns undefined though! some sort of coercion occurs maybe? but then why do we get undefined at the end?

[ericblade]

Numbers are objects of class Number. Objects can have properties, and you can access them with []
... something like that :-)

[cmdcolin]

would be interested in verification of that somehow, my cursory googling is that number is truly a primitive so it would have to be coerced to a object somehow in this process

[ericblade]

1["x"] also equals undefined. Pretty much everything can have properties, and so accessing a property with [] can be a thing on pretty much everything.

I don't have a specific explanation for what happens in the middle :D

looks like the setter for properties on numbers doesn't actually set anything, though