prototype

Sample

From Screencast: Functions, Objects, and Context in JavaScript:

$(document).ready(function() {

  var Person = function(first, last) {
    /**
     * Setting instance properties
     **/
    this.firstName = first;
    this.lastName = last;
    return this;
  };

  Person.prototype = {
    sayFirstName : function() {
      console.log(this.firstName);
    }
  };

  /**
   *  Creating "instances" of Person
   **/
  var adam = new Person('adam', 'sontag'),
      rebecca = new Person('rebecca', 'murphey');

  // adam.sayFirstName();
  // rebecca.sayFirstName();
});