JavaScript Interview Question #42

How does filter() work in JavaScript?

Objects, Arrays & Core Data Handling Junior Beginner

Quick Interview Answer

filter returns a new array containing only the elements for which the callback returns a truthy value. It does not modify the original array.

Detailed Explanation

filter returns a new array containing only the elements for which the callback returns a truthy value. It does not modify the original array.

filter is useful for search results, permission filtering, status filtering, and other cases where a subset of a collection is required.

Code Example

const products = [
    { name: "A", active: true },
    { name: "B", active: false },
    { name: "C", active: true }
];

const activeProducts =
    products.filter(p => p.active);

console.log(activeProducts);