var obj = {
   ObjectA: {fu:'bar'},
   ObjectB: {iheart:'pizza'},
   ObjectC: {something:'value'}
};
var obj2 = {};

var i = 0;
for (var key in obj) {
    obj2[i] = obj[key];
    i++;
}
obj = obj2; // don't really need this - could just use obj2
console.log(obj);