Basic JavaScript Constructor

gistfile1.js

function Person(name, age) {   
  this.name = name;   
  this.age = age; 
}  

Person.prototype = {   
  toString: function() {     
    return this.name + " is " + this.age + " years old.";   
  } 
};  

var john = new Person("John Galt", 50);  
console.log(john.toString());