json - How to access key itself using javascript

Question

I have a JSON like:

  var xx = {'name':'alx','age':12};

Now I can read the value of name which is 'alx' as xx[0].name, but how should I retrieve value of 'name' itself? By that, I mean how can I fetch the key at run time?

Answer 1

for (i in xx) {
    if (xx[i] == "alx") {
        // i is the key
    }
}