You Could Lose Your Mind

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:


I’m not sure that’s mandated by the language spec. It might depend on the implementation. Anyone know?