show filed of object javascript

1var person={"first_name":"Bill","last_name":"Jenner"}
2//get the person object properties with:
3var keys = Object.keys(person); //keys = ["first_name","last_name"]
4

1var getKeys = function(obj){
2   var keys = [];
3   for(var key in obj){
4      keys.push(key);
5   }
6   return keys;
7}

1var keys = Object.keys(myObject);