In javascript how can we identify whether an object is a Hash or an Array?

Question

The output of my JSON call can either be an Array or a Hash. How do I distinguish between these two?

Answer 1

Check for "constructor" property on the object. It is Array - it is an array object.

var a = {
 'b':{length:0},
 'c':[1,2]
}

if (a.c.constructor == Array)
   for (var i = 0; i < a.c.length; i++)
      alert(a.c[i]);
else
   for (var s in a.b);
      alert(a.b[s]);