What happens if you initialize an object with the same key (name) twice? I tried it in FireFox, Internet Explorer, Safari, and Opera.
In all cases, the last assignment (the rightmost one) is the winner.
var obj={a:1,b:2,a:3,b:4};
You end up with an object like this:
{a:3,b:4}
I’m not sure that’s mandated by the language spec. It might depend on the implementation. Anyone know?
Dreaming In JavaScript 