Adding items

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.

Exercise 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.

Show example 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");

Test yourself

Write the addItem body

addItem(product) {
    ____;
}

Show answer

addItem(product) {
    this.items.push(product);
}

Match each method to its job

addItem

Adds a product
push

Appends to array
constructor

Initial setup
this.items

Products array
What does cart.addItem(p) do?
```
cart.addItem(p);
```
- Appends p to items
- Prints the cart
- Removes a product
- Computes the total
Show answer

Appends p to items — addItem appends p to the this.items array.

Next lesson: Calculating totals

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