Prototype Pattern

As we have already mentioned throughout the article, JavaScript does not support classes in its native form. Inheritance between objects is implemented using prototype-based programming.

It enables us to create objects which can serve as a prototype for other objects being created. The prototype object is used as a blueprint for each object the constructor creates.

As we have already talked about this in the previous sections, let’s show a simple example of how this pattern might be used.

var personPrototype = {
    sayHi: function() {
        console.log("Hello, my name is " + this.name + ", and I am " + this.age);
    },
    sayBye: function() {
        console.log("Bye Bye!");
    }
};

function Person(name, age) {
    name = name || "John Doe";
    age = age || 26;

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

    constructorFunction.prototype = personPrototype;

    var instance = new constructorFunction(name, age);
    return instance;
}

var person1 = Person();
var person2 = Person("Bob", 38);

// prints out Hello, my name is John Doe, and I am 26
person1.sayHi();
// prints out Hello, my name is Bob, and I am 38
person2.sayHi();

Take notice how prototype inheritance makes a performance boost as well because both objects contain a reference to the functions which are implemented in the prototype itself, instead of in each of the objects.