Tools to create a functional Shopping Cart - node.js

Question

I'm creating an e-commerce using Reactjs for frontend and Nodejs for backend (also express), and i want to create an shopping cart "connected" to the user account, where the user can recharge the page, close it, and the cart doesn't reset.
I'm looking for tools to create this, or some tutorial to do it with node-express, thanks! (i don't have code yet, cause i don't know from where starts)

Answer 1

This is User Model with Cart( with add-to-cart and remove from cart Function )
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const userSchema = new Schema({
email: {
type: String,
required: true,
},
password: {
type: String,
required: true,
},
resetToken: String,
resetTokenExpiration: Date,
cart: {
items: [
{
productId: {
type: Schema.Types.ObjectId,
ref: "Product",
required: true,
},
quantity: {
type: Number,
required: true,
},
},
],
},
});
userSchema.methods.addToCart = function (product) {
const cartProductIndex = this.cart.items.findIndex((cp) => {
return cp.productId.toString() === product._id.toString();
});
let newQuantity = 1;
const updatedCartItems = [...this.cart.items];
if (cartProductIndex >= 0) {
newQuantity = this.cart.items[cartProductIndex].quantity + 1;
updatedCartItems[cartProductIndex].quantity = newQuantity;
} else {
updatedCartItems.push({
productId: product._id,
quantity: newQuantity,
});
}
const updatedCart = {
items: updatedCartItems,
};
this.cart = updatedCart;
return this.save();
};
userSchema.methods.removeFromCart = function (productId) {
const UpdatedCartItems = this.cart.items.filter((item) => {
return item.productId.toString() !== productId.toString();
});
this.cart.items = UpdatedCartItems;
return this.save();
};
userSchema.methods.clearCart = function () {
this.cart = { items: [] };
return this.save();
};
module.exports = mongoose.model("User", userSchema);
Here, Routes
router.get("/cart", (req, res, next) => {
req.user
.populate("cart.items.productId")
.then((user) => {
const products = user.cart.items;
// console.log(products);
res.render("home/cart", {
path: "/cart",
pageTitle: "Your cart",
products: products,
isAuthenticated: req.session.isLoggedIn,
});
// console.log(products);
})
.catch((err) => {
console.error(err);
});
});
router.post("/cart",(req, res, next) => {
const prodId = req.body.productId;
// console.log(prodId);
Product.findById(prodId)
.then((product) => {
return req.user.addToCart(product);
})
.then((result) => {
// console.log(result);
res.redirect("/cart");
});
});
Tech:-
Frontend:- Ejs View Engine
Backend:- Express, MongoDB Atlas