What does the object[foo] term mean?

Question

I\'m confused what the object[foo] term is referring to. Any hints? I know that bar[\'unique_prop\'] and bar.unique_prop refers to

Answer 1

object[foo] = 'value';

attempts to use an object as a member name, this causes a .toString() call so;

'value' is assigned to object["[object Object]"], when you attempt to read alert(object[bar]); the same toString() occurs as bar is also an object, so you reference object["[object Object]"] once again and get back 'value'.