Javascript: get an array of all property names in an object

arrayOfProperties.js

 keys : function  (o) {
    var accumulator = [];
    for (var propertyName in o) {
      accumulator.push(propertyName);
      }
    return accumulator;
  }

//get values instead of keys
 values : function (o) {
    var accumulator = [];
    for (var propertyName in o) {
      accumulator.push(o[propertyName]);
      }
    return accumulator;
}