Pure Functions are an essential ingredient of functional programming, regardless of the language. In this video we cover the two major rules that make any function pure, benefits of pure function, as well as why some functions can't be pure. Let's have some fun yo!

This is episode 16 of 20 things Javascript Developers Should Know But Probably Don't.

00:00:00 Intro
00:01:15 What is a pure function?
00:01:52 Rule #1: Same input means same output
00:02:58 🔴 Live coding: Rule #1
00:08:37 Benefits of Rule #1
00:10:04 Testability
00:12:05 Rule #2: No side-effects
00:12:22 🔴 Live coding: Rule #2
00:15:07 Benefits of Rule #2
00:16:40 Impure functions 😱
00:18:17 Outro

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JavaScript Promises from the series "20 Things JS Developers Should Know but Probably Don't"
by ColorCode.io, Sina Jazayeri

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