Why does my last customer entry override the previous entry instead of adding it to the customer object? JS

Question

Why does my last customer entry override the previous entry instead of adding it to the customer object? JS Any help would be much appreciated.

class Bank {
    constructor() {
        this.customers = {};


    }
}

Bank.prototype.addCustomer = function (customer) {
    this.customers = customer;
    return this;

}
var bank = new Bank();
var newCustomer1 = bank.addCustomer('Curtis');
var newCustomer2 = bank.addCustomer('Alice');

console.log(bank.customers);

Answer 1

First, customers is not an array, you have declared it as a Javascript Object. Second, when you change it to an array, use the push method to add elements to the end of the array.

I've changed your code accordingly.

class Bank {
    constructor() {
        // Change 2
        this.customers = [];


    }
}

// Change 2
Bank.prototype.addCustomer = function (customer) {
    this.customers.push(customer);

}
var bank = new Bank();
bank.addCustomer('Curtis'); 
bank.addCustomer('Alice');
console.log(bank.customers);