Getting JavaScript object key list

Question

I have a JavaScript object like

var obj = {
   key1: \'value1\',
   key2: \'value2\',
   key3: \'value3\',
   key4: \'value4\'
}

How can I

Answer 1

Note that in coffeescript this can be accomplished in all browsers and node as

k for k of obj

and thus

(1 for _ of obj).length