Skip to content

The JavaScript filter() Function

New Course Coming Soon:

Get Really Good at Git

The details of the `filter()` Function in JavaScript

filter() is a very important method of an array.

This example iterates the array a and builds a new array with elements of a that returned true when running the function f() on each a element

const b = a.filter(f)

A good example of using filter() is when you want to remove an item from the array:

const items = ['a', 'b', 'c', 'd', 'e', 'f']
const valueToRemove = 'c'
const filteredItems = items.filter(item => item !== valueToRemove)
// ["a", "b", "d", "e", "f"]

Here is how you could remove multiple items at the same time:

const items = ['a', 'b', 'c', 'd', 'e', 'f']
const valuesToRemove = ['c', 'd']
const filteredItems = items.filter(item => !valuesToRemove.includes(item))
// ["a", "b", "e", "f"]
Are you intimidated by Git? Can’t figure out merge vs rebase? Are you afraid of screwing up something any time you have to do something in Git? Do you rely on ChatGPT or random people’s answer on StackOverflow to fix your problems? Your coworkers are tired of explaining Git to you all the time? Git is something we all need to use, but few of us really master it. I created this course to improve your Git (and GitHub) knowledge at a radical level. A course that helps you feel less frustrated with Git. Launching Summer 2024. Join the waiting list!
→ Get my JavaScript Beginner's Handbook
→ Read my JavaScript Tutorials on The Valley of Code
→ Read my TypeScript Tutorial on The Valley of Code

Here is how can I help you: