Anjana Vakil — Functional Programming in JS: What? Why? How?

— —
. . Functional programming has become a hot topic in the JS community, leaving many JavaScripters wondering: What's all the hype about? What do functional programs look like, and why might I prefer them to imperative/object-oriented code? How do I get started writing code in a functional style?

If you've been asking yourself these questions, you'll enjoy this gentle, practical intro to functional programming. We'll explore the advantages and basic principles of the paradigm, in which holy, pure functions deliver us from the evils of mutable state. We'll see how rejecting side-effects and mutability in our code can avoid a lot of common JS headaches. And we'll learn how to use core JS features as well as some popular FP libraries like Mori and Ramda to start writing our own functional programs.

[timmark]

You are so good at making complex problems into a very understandable way. This is the best lecture on Functional programming basics.

[montazmeahii]

I'd recommend jumping to 5:23 to save time. At 5:23 she says, "What is functional programming?"

[asmartbajan]

43:53 For those confused about how closure works, the last 3 lines of this example can be expanded as follows:

var holify = (function makeAdjectifier(adjective) {
return function (noun) {
return adjective + ' ' + noun;
};
})('holy');

(function (noun) {
return 'holy' + ' ' + noun;
})('JS');

(function (noun) {
return 'holy' + ' ' + noun;
})('cow');

[briancardona]

Functional programming seems to be a great paradigm and very useful to use in javascript. I really liked the Functional programming talks I've seen lately, like this one. Thanks to Anjana and to HolyJS

[johnyepthomi]

Wow! Learned a lot. Amazing delivery. Thank you so much!

[TubeYouDubeDood]

Great lecture--clearly presented.  I feel that I finally get what others trying to describe functional programming are really talking about.

[gmnboss]

I have watched many functional programming talks online. This is by far the best introduction to FP I have seen in a looong time.

[TheDigitalPrince]

Her presenting skills are really great and natural. Also the concepts are clearly explained.

[francisdez]

I like your sincere, nervous humor. Thanks for keeping it a 1000.

[don-patz-]

Great talk! Was seeking for a track to follow in learning functional and now we have one, thanks to this.

[moulcode]

Explained very well thanks a loot HolyJS

[shibnathroy]

Thank You for this video. I had a lot of doubts about functional programming and now they are clear.

[jubalrahl]

I lover her mind and voice so much!!! 😍

[veer]

One of reasons that I learned to functional programming is performance. For example, using pmap (parallel map) is easy.

[uznemirenapogacica]

I love her lol.Thank you for this awesome introduction!

[steffenlaurens]

Thanks for the closures part, now I know how to do function that returns function with arguments

[abilash_yt_freak]

simpler version of 39:29

function sum(arr, index = 0, total = 0){
if(arr.length === index){
return total;
}
total = total + arr[index];
return sum(arr, index + 1, total)
}

[nathancornwell]

I've been trying to get into functional programming instead of OOP but one thing i can't seem to find an answer on or example of is stepping through an array one element at a time without some state variable that updates what position you are at.

[thomasgdowling]

Great talk! I learned a lot. (At 38.19, line 3, do we need a var/let to keep things 'pure' :-) )

[akaratepongsawang]

I'm worry about system performance to use Recursion instead of Iteration, ECMAScript run an enormous stack on mobile maybe shutdown everything.