Adding items
- Node.js course
- Beginner
- Lesson 49/116
- 6 min
Learn to add items with the addItem method.
The addItem method
The Cart class is ready; now we will write an addItem method to add products to the cart. The Cart class's items array is already initialized as empty in the constructor; this array holds the added products.
The addItem(product) method calls this.items.push(product) in its body, which appends the product to the end of the array. A product is an object with { name, price, quantity } fields. For example cart.addItem({ name: "Notebook", price: 25, quantity: 2 }) adds a notebook product.
push and array append
.push(x) appends an element to the end of an array and returns the new length. items.push(product) places product at the end of items; the array length grows by one.
To add several products you call addItem once per product. For example adding two products: cart.addItem(p1); cart.addItem(p2);. Each call places one more element in the items array; insertion order is preserved. push appends at the end; to prepend use unshift.
Practice Write the addItem method
Add an addItem method inside the Cart class. Its signature must be addItem(product). The body should call this.items.push(product);. The main part already adds a product and prints added; you only need to write the method. The output on a single line must be added.
Starter code
class Cart {
constructor() {
this.items = [];
}
}
// Write the addItem method here
}
// Test
const cart = new Cart();
cart.addItem({ name: "Notebook", price: 25, quantity: 2 });
console.log("added");Sample solution
class Cart {
constructor() {
this.items = [];
}
addItem(product) {
this.items.push(product);
}
}
// Test
const cart = new Cart();
cart.addItem({ name: "Notebook", price: 25, quantity: 2 });
console.log("added");Expected output
added
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Write the addItem body
addItem(product) {
____;
}addItem(product) {
this.items.push(product);
}Explanation: this.items.push(product) appends the product to the array.
2 Match each method to its job
| Term | Meaning |
|---|---|
addItem |
Adds a product |
push |
Appends to array |
constructor |
Initial setup |
this.items |
Products array |
3 What does cart.addItem(p) do?
cart.addItem(p);- Appends p to items Correct answer
- Prints the cart
- Removes a product
- Computes the total
Explanation: addItem appends p to the this.items array.