This chapter delves into the intricacies of the filter() method, elucidating its syntax, applications, and how it facilitates the creation of refined arrays.

filter()

The filter() method selects elements that meet a particular condition. Let's decipher the syntax:

array.filter((element, index, array) => {
  // Callback body
});

Here's what we need to know about the filter() method:

• It does not alter the original array;
• It iterates over the original array element by element;
• It returns a new array;
• Elements are added to the new array if they satisfy the callback condition;
• If the callback returns true, the element is included; otherwise, it is omitted.

Examples

The true prowess of the filter() method becomes apparent when applied to diverse scenarios. Let's delve into some illustrative examples:

Example 1: Filtering Odd Numbers

In this example, the filter() method creates an array (oddNumbers) comprising only odd numbers from the original array.

Example 2: Filtering Products by Price Range

Here, the filter() method is utilized to extract products with prices below $500, creating a new array (affordableProducts).

const products = [
  { name: "Keyboard", price: 220 },
  { name: "Smartphone", price: 800 },
  { name: "Tablet", price: 500 },
  { name: "Headphones", price: 120 },
  { name: "Camera", price: 1500 },
];

const affordableProducts = products.filter((product) => product.price < 500);
console.log(affordableProducts); // Output: [ { name: "Keyboard", price: 220 }, { name: "Headphones", price: 120 } ]