Question

If you have an array of product objects created from JSON, how would you add a prototype method to the product objects so that they all point to the same method? How would you train JavaScript to recognize all product objects in an array are instances of the same class without recreating them?

If I pull down a JSON array of Products for example, and want each product in the array to have a prototype method, how would I add the single prototype method to each copy of Product?

I first thought to have a Product constructor that takes product JSON data as a parameter and returns a new Product with prototypes, etc. which would replace the data send from the server. I would think this would be impractical because you are recreating the objects. We just want to add functions common to all objects.

Is it possible to $.extend an object’s prototype properties to the JSON object so that each JSON object would refer to exactly the same functions (not a copy of)?

For example:

var Products = [];
Products[0] = {};
Products[0].ID = 7;
Products[0].prototype.GetID = function() { return this.ID; };
Products[1].ID = 8;
Products[1].prototype = Products[0].prototype;  // ??

I know that looks bad, but what if you JQuery $.extend the methods to each Product object prototype: create an object loaded with prototypes then $.extend that object over the existing Product objects? How would you code that? What are the better possibilities?

Answer 1

So, if I’m getting this all correctly, this is a more complete example of KOGI’s idea:

// Create a person class
function Person( firstName, lastName ) {
    var aPerson = {
        firstName:  firstName,
        lastName:   lastName
    }

    // Adds methods to an object to make it of type "person"
    aPerson = addPersonMethods( aPerson );
    return aPerson;
}
function addPersonMethods( obj ) {
    obj.nameFirstLast = personNameFirstLast;
    obj.nameLastFirst = personNameLastFirst;
    return obj;
}
function personNameFirstLast() {
    return this.firstName + ' ' + this.lastName;
}
function personNameLastFirst() {
    return this.lastName + ', ' + this.firstName;
}

So, with this structure, you are defining the methods to be added in the addPersonMethods function. This way, the methods of an object are defined in a single place and you can then do something like this:

// Given a variable "json" with the person json data
var personWithNoMethods = JSON.parse( json );    // Use whatever parser you want
var person = addPersonMethods( personWithNoMethods );