Learn about the fundamentals and common design patterns of JS.

Become an AdonisJS Developer

This module is for those who are familiar with the basics of JavaScript and looking to advance their knowledge and really understand how the language works. We'll cover topics that are essential to help you read, understand, and write better code. Before starting, you should be familiar with the basics of variables, functions, and loops in JavaScript.

This module will enable you to master JavaScript concepts that stump most developers.

A Comprehensive Guide to Intermediate JavaScript

## Array.filter

The idea here is similar to Array.map, except instead of transforming individual values, we want to filter existing values. Without any functions (besides [Array.push](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push?v=example)), say we want to filter out values in an array that are less than 5:

### for-loop

# Array.filter

The idea here is similar to Array.map, except instead of transforming individual values, we want to filter existing values. Without any functions (besides [Array.push](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push?v=example)), say we want to filter out values in an array that are less than 5:

## for-loop

Learn how `Array.filter` works by learning how to write it yourself. It's almost as powerful as `map` and used ubiquitously throughout code.

Before We Begin

Behaviour of Functions and Variables

Essential Modern JavaScript - ES2015+ In Depth

Object Oriented Programming: The Core

Object Oriented Programming: `this` and Inheritance

Introduction to Functional Programming

Functional Programming: Arrays and their Powerful Methods

Functional Programming: Objects and their Powerful Methods

A Dive into Asynchronous JavaScript

Advanced Modern JavaScript - Cutting Edge ES2015+

Conclusion

Filter

Array.filter