日々特訓

何事も基礎が大事。
指示を見ながら、学習サイトで日々知識をため込んでいます。
FreeCodeCamp以外にも良いサイトがあれば教えてほしい。
下は演習問題のまとめ。

const cartContainer = document.getElementById("cart-container");
const productsContainer = document.getElementById("products-container");
const dessertCards = document.getElementById("dessert-card-container");
const cartBtn = document.getElementById("cart-btn");
const clearCartBtn = document.getElementById("clear-cart-btn");
const totalNumberOfItems = document.getElementById("total-items");
const cartSubTotal = document.getElementById("subtotal");
const cartTaxes = document.getElementById("taxes");
const cartTotal = document.getElementById("total");
const showHideCartSpan = document.getElementById("show-hide-cart");
let isCartShowing = false;

class Dessert {
  constructor(id, name, price, category) {
    this.id = id;
    this.name = name;
    this.price = price;
    this.category = category;
  }
}

const products = [
  new Dessert(1, "Vanilla Cupcakes (6 Pack)", 12.99, "Cupcake"),
  new Dessert(2, "French Macaron", 3.99, "Macaron"),
  new Dessert(3, "Pumpkin Cupcake", 3.99, "Cupcake"),
  new Dessert(4, "Chocolate Cupcake", 5.99, "Cupcake"),
  new Dessert(5, "Chocolate Pretzels (4 Pack)", 10.99, "Pretzel"),
  new Dessert(6, "Strawberry Ice Cream", 2.99, "Ice Cream"),
  new Dessert(7, "Chocolate Macarons (4 Pack)", 9.99, "Macaron"),
  new Dessert(8, "Strawberry Pretzel", 4.99, "Pretzel"),
  new Dessert(9, "Butter Pecan Ice Cream", 2.99, "Ice Cream"),
  new Dessert(10, "Rocky Road Ice Cream", 2.99, "Ice Cream"),
  new Dessert(11, "Vanilla Macarons (5 Pack)", 11.99, "Macaron"),
  new Dessert(12, "Lemon Cupcakes (4 Pack)", 12.99, "Cupcake"),
];

products.forEach(
  ({ name, id, price, category }) => {
    dessertCards.innerHTML += `
      <div class="dessert-card">
        <h2>${name}</h2>
        <p class="dessert-price">$${price}</p>
        <p class="product-category">Category: ${category}</p>
        <button 
          id="${id}" 
          class="btn add-to-cart-btn">Add to cart
        </button>
      </div>
    `;
  }
);

class ShoppingCart {
  constructor() {
    this.items = [];
    this.total = 0;
    this.taxRate = 8.25;
  }

  addItem(id, products) {
    const product = products.find((item) => item.id === id);
    const { name, price } = product;
    this.items.push(product);

    const totalCountPerProduct = {};
    this.items.forEach((dessert) => {
      totalCountPerProduct[dessert.id] = (totalCountPerProduct[dessert.id] || 0) + 1;
    });

    const currentProductCount = totalCountPerProduct[product.id];
    const currentProductCountSpan = document.getElementById(`product-count-for-id${id}`);

    currentProductCount > 1 
      ? currentProductCountSpan.textContent = `${currentProductCount}x`
      : productsContainer.innerHTML += `
      <div id="dessert${id}" class="product">
        <p>
          <span class="product-count" id="product-count-for-id${id}"></span>${name}
        </p>
        <p>$${price}</p>
      </div>
      `;
  }

  getCounts() {
    return this.items.length;
  }

  clearCart() {
    if (!this.items.length) {
      alert("Your shopping cart is already empty");
      return;
    }

    const isCartCleared = confirm(
      "Are you sure you want to clear all items from your shopping cart?"
    );

    if (isCartCleared) {
      this.items = [];
      this.total = 0;
      productsContainer.innerHTML = "";
      totalNumberOfItems.textContent = 0;
      cartSubTotal.textContent = "$0";
      cartTaxes.textContent = "$0";
      cartTotal.textContent = "$0";
    }
  }

  calculateTaxes(amount) {
    return parseFloat(((this.taxRate / 100) * amount).toFixed(2));
  }

  calculateTotal() {
    const subTotal = this.items.reduce((total, item) => total + item.price, 0);
    const tax = this.calculateTaxes(subTotal);
    this.total = subTotal + tax;
    cartSubTotal.textContent = `$${subTotal.toFixed(2)}`;
    cartTaxes.textContent = `$${tax.toFixed(2)}`;
    cartTotal.textContent = `$${this.total.toFixed(2)}`;
    return this.total;
  }
};

const cart = new ShoppingCart();
const addToCartBtns = document.getElementsByClassName("add-to-cart-btn");

[...addToCartBtns].forEach(
  (btn) => {
    btn.addEventListener("click", (event) => {
      cart.addItem(Number(event.target.id), products);
      totalNumberOfItems.textContent = cart.getCounts();
      cart.calculateTotal();
    });
  }
);

cartBtn.addEventListener("click", () => {
  isCartShowing = !isCartShowing;
  showHideCartSpan.textContent = isCartShowing ? "Hide" : "Show";
  cartContainer.style.display = isCartShowing ? "block" : "none";
});

clearCartBtn.addEventListener("click",cart.clearCart.bind(cart));