Number of elements in a javascript object

Question

Is there a way to get (from somewhere) the number of elements in a javascript object?? (i.e. constant-time complexity).

I cant find a property or method that retriev

Answer 1

function count(){
    var c= 0;
    for(var p in this) if(this.hasOwnProperty(p))++c;
    return c;
}

var O={a: 1, b: 2, c: 3};

count.call(O);