JavaScript Array Reduce Method Practice in 5 Minutes

Learn to use the Reduce() function to convert an array of items to one output (ex. sum of items in an array).

Arrays are an essential part of JavaScript. If you want to get better at JavaScript, you have to know how to effectively use arrays, especially the built-in array methods like map, reduce, filter, sort, every, some, etc. In this series, we'll cover the JavaScript array methods you need to know to become a web developer.

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COURSES 💻

[bargm]

Just what i'm looking for. Great work. I'm a time SQL programmer and new to javascript (which is my new retirement hobby). I was always wondering how in javascript to do a simple "Select EyeColour, count(*) from Characters group by EyeColor". This has opened my eyes! (Which are blue by the way if you need to add that to the data set. 😁)

[KieCodes]

5 minutes well spent. Great video. Concepts from functional programmers should be in every developer's toolbox! Thank you for making this! 🙏

[my_j.a.r.v.i.s.]

Thanks for making these short videos. They're very helpful.

[aaronlinton-chambers]

I love the way your simplify difficult topics in a manageable way

[dlongodesign]

The best video I found with Reduce() examples. THANK YOU SO MUCH!!

[MYount]

Thank you for explaining this so clearly and concisely.

[theoglossa]

Great stuff! I'll always go back to this playlist!

[davidjohansson]

Great series on the JS array methods, thanks!

[RhoTrepaan]

This was quicker than ‘looking it up’ thanks 👍

[jaydenmoon]

First time watching your vids - this was an easy sub for me - really love your vids and explanations - it has been helpful - thank you

[chubbyBunny]

Back again for a refresher; by far the most extensive tutorial on this topic

[GabrielMazzoleni]

The eye color example was really good, thanks

[bradpeters]

I gave you a thumbs up. The video is mostly clear. I wish you would have explained why you started with an empty object. With that being said I have seen several examples of using the reduce method with objects and this is one of the more clear explanations even though I do not understand why you start with an empty object.

[JimKernix]

This and the map vieo were helpful - thanks! I forgot to sub to your channel when I saw your video on Brad Traversy's channel.

[olivierdeplanques]

Very interesting, good video, thanks a lot

[robinstahlwarelius]

Great videos! Thx man :)
PS color theme do you use?

[DhanByCode]

My English is not very good but I really understand it with your explanation, I like your style in explaining and the font used is quite pleasing to the eye with an explanation and a font size that is very suitable and comfortable to see and hear, awesome .. I hope you explain more in detail like this and more tutorials about javascript on your channel cz this tutorial is great!

[sateeshnaidu]

Hi James Q Quick, your tutorials are simply awesome, In reduce function example the output of totalMass producing incorrect result(0497784136), we have to apply parseInt to curr.mass i.e characters.reduce((acc, cur) => acc + parseInt(cur.mass), 0). so that we will get correct result(346). Thanks for your Great Tutorials.

[ayodejijoseph]

I wonder the people giving thumbs down for this lovely easy to understand video 🤔, can we see something better from you lots giving thumbs down then.

[phickman]

Yet another awesome video!! Love the explanations because they are so easy to follow.