How to implement references between objects in javascript

Question

I am looking for the correct way to store references to objects in javascript.

For example I have an object customer:

function Customer(n) {
  this.name = n;
}

And an array of all customers, that gets filled:

var customers = new Array()
customers.push(new Customer('Alfred'));
customers.push(new Customer('Bob'));

Now I also have several other objects which reference customers, like purchase, and outstandingOffer, promotion ect. which should all reference to elements of the customers array. For example:

function Purchase(i, c) {
  this.customer = c; // ? <- this need to be a reference
  this.item = i; 
}

This could be done by storing the index in the array, but that seems fragile in case a customer needs to be removed. What is the best way to store a reference to another object in javascript?

repzero · Accepted Answer · 2016-01-02 03:34:32Z

looking at below you approach is different

var customers = new Array()
customers.push(new Customer('Alfred'));
customers.push(new Customer('Bob'));

You are pushing new objects in an array without saving a reference to it.So your purchase function will never know what is who or who is what

This is How I would approach it

function Customer(n) {
  this.name = n;
  this.items=[];
  this.addPurchase=function(item){
  this.items.push(item);
  }
}

The above function will have the follow

The name of the customer
A function that adds an item to the customer item cart
An item cart

var customers = {}; //create a big object that stores all customers
customers.Alfred=new Customer('Alfred'); // create a new object named Alfred
customers.Bob=new Customer('Bob'); // create a new object named Bob
customers.John=new Customer('John'); // create a new object named John

Using console.log, you will get

Alfred: Object, Bob: Object, John: Object

If you want to add items to Alfred you do this

customers.Alfred.addPurchase('pineapple');

If you want to add items to Bob you do this

customers.Bob.addPurchase('mango');

If you want to add items to John you do this

customers.John.addPurchase('coconut');

This is output from console.log(customers.John.items);

Array [ "coconut" ]

So what if we want to delete a customer? We already have a reference to it!

delete customers.John;

John and this history is gone!...Verify it is deleted

console.log(customers);

output

Object { Alfred: Object, Bob: Object }

Scarecrow · Accepted Answer · 2016-01-01 23:07:31Z

0

use new to create object

var customers = new Array()
customers.push(new Customer('Alfred'));
customers.push(new Customer('Bob'));

function Purchase(i, c) {
  this.customer = c; // ? <- this need to be a reference
  this.item = i; 
}

var Purchase_obj = new Purchase(2,customers[0] );

edited Jan 1, 2016 at 23:07

answered Jan 1, 2016 at 23:05

Scarecrow

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2 Comments

Beginner Over a year ago

if I change the name of the customer, will that show up in the purchase? what happens when a customer in customers gets deleted?

Scarecrow Over a year ago

@Beginner if you update customer name that will reflect in purchase object, that is the main concept of oop , if you remove one customer from customers array it will not be destroyed, you can still get customer name from purchase object

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