ECMAScript 5 Objects and Properties

ecmascript5-objects.js

var ns = ns || {};

ns.PropertyUtils = {
 
  // Make the named (or all) properties of o nonenumerable, if configurable.
  hide : function(o) {
    var props = (arguments.length == 1)
        ? Object.getOwnPropertyNames(o)
        : Array.prototype.splice.call(arguments, 1);
    props.forEach(function(p) {
        if (!Object.getOwnPropertyDescriptor(o, p).configurable) return;
        Object.defineProperty(o, p, { enumerable: false });
    });
    return o;
  }
    
}

ns.Point = (function() {
 
  function Point(x, y) {
    this.x = x;
    this.y = y;
    Object.freeze(this);
  }
  
  Point.prototype = ns.PropertyUtils.hide({
    constructor: Point,
    add: function(other) {
      return new Point(this.x + other.x, this.y + other.y);
    },
    isEqualTo: function(other) {
      return this.x == other.x && this.y == other.y;
    }
  });
  
  return Point;

}());

var point1 = new ns.Point(3, 1);
var point2 = new ns.Point(2, 4);
point1.x = 2;
show(point1);
show(point2);
show(point1.add(point2));

for (prop in point1) {
     print(prop);
}