Updating the Count of Products in Cart

//app/services/cart-service.js
import Service from '@ember/service';
import { tracked } from '@glimmer/tracking';
class Product {
    @tracked count;
    product_id;
    title;
    desc;
    source;
    price;
  
    constructor(product) {
      this.product_id = product.product_id;
      this.count = product.count;
      this.title = product.title;
      this.desc = product.desc;
      this.source = product.source;
      this.price = product.price;
      this.total = product.total;
    }
  }
  
export default class CartServiceService extends Service {
  @tracked productsList = [];
  addProduct(product) {
    const existingProduct = this.productsList.find(({ product_id }) => {
      return product_id == product.product_id
    });
    if (existingProduct) {
      existingProduct.count += 1;
      existingProduct.total = existingProduct.price* existingProduct.count;
    }
    else {
      this.productsList = [
        ...this.productsList,
        new Product({
          ...product,
          count: 1,
          total : product.price
        }),
      ];
    }
  }
}