Intermediate React.js Coding Interview (ft. Clément Mihailescu)

I give Clément an intermediate level React.js coding interview where I test his knowledge in creating a table that can sort columns and search for values.
Code: codesandbox.io/s/quizzical-th...
Checkout the interview I did on Clément's channel: • Medium Google Coding I...
Previous beginner React.js interview: • Beginner React.js Codi...
#benawad ​
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#benawad

[@bawad]

Checkout the video we made on Clément's channel where I do an intermediate Algo interview: kzbin.info/www/bejne/aqW8oImuZbaihJI

[@alhajee]

That smile on your face at 13:00 seeing Clement over-engineer. Simply maping the values would have solved the problem

[@clem]

This intermediate React interview was fun, but now I wonder… How fun would a *hard* React interview be? 👀

[@neethology]

Good question, no sweat for you.

[@Yassinebridii]

An advanced coding Interview would be cool to see too.

[@robinsu3796]

I think it’s time for redux then

[@ryanspivey1819]

bro you need to shave

[@tkdevlop]

Implement react Reconciliation In 45 mins

[@jihadkhawaja]

Fun fact, Ben was too lazy to do it so he made this interview up so Clement finish it for him

[@ManavKaushal]

more like a plot twist

[@TheoParis]

@@ManavKaushal LOL yes

[@RohitKumar-ly6pb]

😂😂

[@divyanshusah2809]

🤣🤣F

[@firstdev1653]

Ben: can you flatten this simple object? Clément: sure here is a recursive linear time complexity algorithm to flatten every possible object in the world

[@aurorapaisley7453]

How to flatten

[@thebonvoyageduo]

my thoughts exactly 😆

[@negasonicteenagewarhead]

But it's easy?

[@merlin6962]

I have never seen someone over engineering a simple task like that. Respect!

[@samgord4669]

this is the comment i was looking for. #respect

[@brothercaleb]

😂

[@qreamybean]

I came looking for this comment. I was in awe the entire time! haha

[@slolom001]

Yeah I was thinking the same thing. Wtf?? Was there a point to that?

[@Jindujun]

yeah, I was shaking my head sometimes but I guess thats how amazing minds work xD

[@efdezpolo]

We started with a table, now we have an AbstractTableHeaderGeneratorFactory

[@inordirection_]

lmao

[@xit]

The title should be "Dynamically flattening objects in javascript with Ex-Googler - Clément Mihailescu " XD

[@sammusaev5883]

"Babe, it's 4pm. Time for your dynamic object flattening. "

[@smoothbeak]

That dude worked at Google :P?

[@xit]

@@smoothbeak Yeah! No Cap XD

[@webdevinterviewtrainingusa1494]

kzbin.info/www/bejne/rn2qq2enisRjmKM

[@Avoidlol]

lmao, so true. never heard the word "flattened" so many times in 30 minutes

[@Justenphelps]

Ben, your smug smile during the interview would simply make me shit myself thinking I was always wrong.

[@RohitKumar-ly6pb]

😂😂😂

[@monome3038]

agree xD

[@kiranpillai876]

I died laughing every time Ben did that

[@josesoto3594]

Man i was like shit they think so fast... then I realized i watch yt on x2

[@shamimahmedrian4222]

This is hilarious

[@satyasrikar709]

this is so funny xD

[@vinayvarma266]

Same with typing speed

[@splasher2119]

It's hard to believe that you were watching on 2x and never noticed 😕 maybe say something more realistic next time

[@unarei]

@@splasher2119 I watch everything on 2x so I don't notice it usually

[@crvlwanek]

Look at how happy Ben is when there's not a graph matrix involved

[@railguns]

me: I know React, Vue, Svelte and SEO best practices. my interviewer: good. please solve riemann hypothesis with the least space & time complexity. I will give you 10 minutes to solve. good luck.

[@cryptonative]

lucky they didn’t ask to center a div

[@gountaa]

@@cryptonative #myUglyDiv{ left : calc( 50% - somebullshit value that makes my div looks almost centered); }

[@TheoParis]

@@gountaa i just use flexbox

[@paucolome4298]

@@gountaa bruh

[@gountaa]

@@paucolome4298 It's best practice trust me i read it on a 14 years old stack overflow post

[@thefakedeal]

Watching him flatten the object really made my head hurt

[@kadensharpin2156]

It was unnecessarily over complicated

[@thesupercoach]

@@kadensharpin2156 Agreed. He read too much into it, got told he read too much into it and decided to keep going anyway.

[@Aurora99aroruA]

Yeah that got overcomplicated by simultaneously introducing dynamically generating the keys / table headers, which is kind of unrelated other than it becoming more complex in a context of flattening. It is a requirement by itself with pros and cons, the latter being that your table will look different depending on your input (first input in this case). There was no requirement for this at all as I understood the assignment.

[@wizard_of_az]

He had overcommitted to his intuition while missing the que from the interviewer to simplify the solution. So fun to come across this while working...

[@hstandeffer]

I’m sure being around algo based problems all day makes you think the simplest approach is never right when in this case it obviously was

[@Souljacker7]

I love watching people way smarter than me struggling with things that are fairly simple to me!

[@timm8998]

How do you know he is smarter?

[@MyKneeHurts]

maybe because he is at an advanced level of programming within just a couple of years of starting, along with the fact that he did math at uPenn. idk tho@@timm8998

[@sabukuna]

@@timm8998 i guess the way he over-engineered it

[@dan_vl1909]

I am grateful that I got Clement's video recommended, these kind of videos does it job when you are not too deep in some stuff. Like in this scenario, frameworks. I've understood a lot about React with these two videos (and also the long video that wrapped all React hooks tutorials)

[@Vilhena6969]

I loved the fun vibe around this coding session ;) looking forward for part 3 - hard mode

[@Gohel95]

I was waiting for it from a while.. thanks, ben💕

[@dbmscreen]

TIL the Clement full text search. Thank you Clement I like it! Astig!

[@azsamsiizbrah]

Damn this stringify moment was hilarious! Great creativity, love the interview

[@jay-pitroda]

18:40 Ben: what have I got my self into

[@show_me_the_moneyy]

Loved this one , this kind of content is what differentiates Ben from other content creators. Loved the coding exercise, it was interesting

[@ankitbatra270]

53:01 *Ben bursting out laughing* "Do you have prod code that does this?? 😂"

[@handsomecat7225]

Unbelievably useful video for me. Thank you both!

[@TheAwesomeness490]

Ben is one of the only youtubers that I don’t have any second thoughts about watching videos longer than 30 mins

[@alex__coder]

Nice interview, love to watch more intermediate interviews.💓

[@shivamsahil3660]

I loved the way this guy implemented recursion effortlessly. I keep struggling a lot with recursion at times... Also I realized I was watching it at 2x speed.

[@prasunkumar_]

I recently had to implement this kind of table where the table had bunch of row & colum level actions and a annoying nested object to deal with and I can feel Clement here! And to increase the complexity the table was live that is it was continuously getting updates from a live feed and to implement sort, filter to that etc. Was another ball game.

[@sadhlife]

36:28 sort function: works first try Ben, knowing the pains of javascript development: "beautiful"

[@nickwoodward819]

This is amazing, do more of this :D

[@mexicanmax227]

Question for Ben and Clément! Can y’all each make a video for best practices in React in front end and best practices in Python for algorithms?

[@dragonborn1996]

Just came from the beginner React coding interview with Clement. Again, this was super informative and helpful. A bit let down you didn't make Clement add authentication like you said you would in the previous video but its all good haha. Awesome vid!

[@ninjaasmoke]

What a trip down memory lane! I had just started learning React when I saw the previous interview. I'm still learning, but ik all the things done in this video

[@saikumar880120]

Any tips on learning react? good website to study? approach? and all that

[@carloseustaquio7785]

Wow, Clememént struggled with the flat obj stuf man

[@lonestarstatechris]

I completed a full stack boot camp with js/react/node. It began 9/19, but ended 3/20 right as pandemic started. Knew I wasn’t going to find a job right away so went right into a data science boot camp that promised a job as long as you finish. Got a job as an analyst and hardly even doing any programming now, just a little Python on the side. Originally got into it because I loved learning to code and now getting back into the dev side. I personally love JS and React so much more than Python. I have used a little Flask, but React just seems more enjoyable to me. These videos are helpful to get me ready to search for a role that allows me to use both skill sets. Thx

[@Lo323984]

All this dynamic flattening might be neat in other use cases, but since this is TS, and a presumably well-defined API response that doesn't have too many fields, creating an interface and working with defined object keys would be so much easier IMO. Specifying an interface (or multiple) for the API response would have been my first step actually.

[@jkho8365]

What's ur thought on .then vs await?

[@danshilm]

@@jkho8365 I default to using await and only use .then if I have a good reason to.

[@jkho8365]

@@danshilm same I use await too. Seeing Clement do it and not sure if there's a good reason too tho

[@danshilm]

@@jkho8365 the 2 are almost identical in the way they work, in performance and the only big difference I've found is when handling errors. There's a long article about it on the v8 blog if you want to read about the technical details of this - this is the relevant section: v8.dev/blog/fast-async#await-under-the-hood

[@jkho8365]

@@danshilm thanks

[@mahdijafaree5332]

I love the way you code!

[@amysheeter877]

Watching Ben watch Clem over engineer is better than any comedy show I've ever seen.

[@madomation7984]

I like how both of them interview each other

[@MohitKumar-tn1cf]

Its was great to see, keep it up!!

[@harishraju4321]

superb timing.....thanks for this

[@guanxi99]

One hour coding without looking anything up on the web or pasting something from stackoverflow? Cudos!

[@viet.khoaiegg]

Learning so much, thanks for good contents 👌

[@sandeeptottadi]

Need more like this ben

[@inordirection_]

I was just building a little react app which has a couple table-based displays, was thinking of adding column based sorting and a search function so this is great. Now I just need to get Clem to do a mock interview with me

[@brothercaleb]

Kudos to Clement for putting himself on the spot. 👏🏽👏🏽👏🏽👏🏽

[@brandongoldsmith1765]

It’s crazy I literally had to do this this week for my react internship! Wow I’m an intermediate now

[@kokokok7171]

Not like you can come up with all this from just your mind

[@empyrean5330]

Haha watching this fresh off of the intermediate Algo Interview on Clement's channel. Tons of fun and I hope you guys can take a shot on a 'Hard' mode sometime!

[@smoothbeak]

I'm only 8 minutes in, but I have to say this is a really wonderful video, and helpful for those getting in to the industry. In addition I also appreciate the high resolution video, that just makes it that little more enjoyable and easier to follow.

[@DanOhCaptainDaniel]

This is great. Can we do like 50 more of these?

[@TotallyNotZoid]

I feel good knowing that few years ago I didn't even know what DOM is and now I can easily do all of these things!

[@tny7390]

so glad i watched all the way, watching ben laugh at JSON.stringify is priceless

[@marcusaureliusregulus2833]

Lol. Is it slow? Or why did he laugh so much😂

[@kevinbatdorf]

pro tip: using the index as the key attribute is an anti pattern. Use something unique to the item instead (and make sure it’s a primitive type)

[@jimmyliao6429]

Yes, especially you have sorting feature.

[@joecamroberon9322]

Yea I remember reading about this recently. It worsens performance because it messes with React’s reconciliation process. When you have indices for a key and you move elements around, React loses track of what was updated/added/removed due to the same key switching nodes. I think this is how it happened at least

[@akj3344]

@@joecamroberon9322 correct.

[@kevinbatdorf]

@Sebastian Voráč be careful with that too because it will bust the cache if sorting happens, making your app less performant.

[@DiegoMartinez-hs3jh]

been waiting for thissssss

[@abhishektripathi1323]

It helped a lot. I was nervous about how much I know. At least now I don't doubt myself.

[@abhishekvishwakarma9045]

Watched 1st part when I am beginner😅 in react now I am working in a company as a full stack it's been so long 😆

[@DaJukes]

working in india?

[@sur_shrimpster]

@@DaJukes why does it matter? smh 😑

[@ahmadmuslih]

@@sur_shrimpster bruh chill he just asked

[@karthik_sama]

Where do u work bro?

[@Vilhena6969]

me too :D

[@thomasgipson7120]

Ben's subtle smirks make it so funny. Wayyyy too much for that simple task lol

[@yulongwang249]

Most of the people won’t be able to do this much given the same amount of time, so definitely impressive there. One thing I think would be helpful for the viewers is to explain different ways to structure the code so that the code is more maintainable and performant :)

[@mohamedsawaed3834]

This is great interview. I have an interview on thursday for fullstack position. Hope it goes well🙏🙏

[@dealloc]

I always tend to store the transformed data for display in component state, since that state is tied to the UI. This gives you a single source of truth, easier to maintain, and makes debugging much easier, since the state reflects exactly what will be displayed. And as you may have noticed in the video, you can avoid having to change any UI output in some cases-like adding a sorting functionality. If I use global state management, I tend to also store the transformed data there, except if a component does something special with the data that is not compatible with other components that share that same state.

[@jfklittle]

This is gonna be top notch content

[@Musa-lf5yn]

I was an Angular developer when I watched the first part. I moved to react recently.😅

[@syedalimehdi-english]

Have been waiting for this...

[@Aurora99aroruA]

I totally respect that this is all on-the-spot (which makes it great to watch but not suitable for educating beginners), so it's a bit unfair to judge you from the armchair, but some remarks anyway. The flattening vs dynamic has been mentioned, but the sorting function sorting on what the sort order will (presumably) become later on, is unnecessary coupling (just reorder the lines so that newSortingDirections is determined before sortData) . Reversing the sort could also be done by switching a and b at the start, or multiplying the result by -1 for reverse. I 'feel' there's a bit much intermediate variable creation to my taste, but Code Complete would probably approve :)

[@clivend]

possible titles: "why you are ready for FAANG but you don't know yet", "exposing youtube coders"

[@justanotherhotguy]

Interviews are fun. I’m eighteen and will soon will be questioned. Watching you guys helps me to cool down a bit, but I still fear to get negative experience from one. Thank you.

[@Azrael1793]

damn that curly brace smash of JSON.stringify was cold. Thanks to both for the video, it kinda went off track (to me) in the first part with the overengineering but can't complain!

[@okey5818]

Clement is an algo and interviews hero. But I would never let him write production React code :D

[@JohnDoeX1966]

Why not? He seems smart to me

[@tiejeevan]

Fuck that, it's 3 line code. Instead he wrote 30 freaking lines

[@Jindujun]

@@JohnDoeX1966 because he overcomplicates simple problems.

[@JohnDoeX1966]

Jindujun oh okay

[@mayankjha7444]

@@tiejeevan but he thought and countered on the fly.

[@yaku-tecnologia2650]

I guess Ben had a 10 line code solution for this. Thats why Front End could be so hard and easy at the same time!

[@jason17493]

awesome showdown!!

[@vijaynavale3919]

🤣🤣ben bhai you are bohot hard🔥🙏

[@forbiddensongs]

this has to be a good example of over-engineering failing you an interview. not only was it severely over-engineered, it also wasn't really a good solution. why would you ever want to get data from an API and dynamically display everything it returns? you have no control over what you display. either way, cool vid ;>

[@BG-fo4si]

18:41 Ben be like "What the heck, Clement XD"

[@Charger285]

They back!!

[@julian_handpan]

Stackoverflow: flat array js Copy, paste Continue Less than 1 minute 🤯

[@imthiyazmuhammed2517]

I thought ben is introducing clement , when youtube showed me algoexpert's ad 😁

[@lhrsupun]

just beautiful

[@letsgocamping88]

Ben looks like he’s finally seen some sun! ☀️

[@charlesjeremiahcansino2244]

that json.stringify made my day 😂

[@fullstack_journey]

U could store 1 or -1 as sorting direction and multiply them with -1 to get the appropriate return values sortingDirection = 1 if a < b, return sortingDirection * -1 if a > b, return sortingDirection if a = b, return 0

[@marcoriolo9549]

Well now I feel more confident in my skills, having it done in a fraction of the time hahaha

[@Avoidlol]

the point of an interview like this is not for you to do it as fast as possible, it's to show off the way you approach problems and the way you think. any beginner can do these tasks obviously

[@samgord4669]

ok so, i just wanna share my react interview experience for a job i did not get. i've been working with react on and off in the past 3 years. i watched these two videos to see if i'm ok or not and both of these videos were too easy for me. i also passed the first assigned coding challenge the company gave me, it was nothing but fetching, rendering and filtering data based on an input field and writing some tests for it. but the reason i failed the interview and did not get the job was the following questions that i couldn't answer properly : 1- what is virtual dom and what are the benefits of it? 2- how to test an endpoint on the front end ? 3- we know we should update the state in an immutable way, but why? what happens if we don't ? 4- what is the event loop? 5- what are pure functions? ---- there were other questions that i answered like about closures or higher order components. but the 5 above took me down. honestly i'm a little mad about the 1st and 4th question, because i don't really understand how knowing the answer to them makes me a better dev. but anyways... make sure you know the answer to these. happy coding!

[@cosmin4437]

Do you know the answers now for 2, 3 and 5? 😇

[@unpluggedaman]

This was super helpful. Thanks a lot

[@HaibertBuilds]

the way he casually dropped a recursion solution.. sheeeesh

[@bodolawale5448]

I don't really know react but I loved watching this

[@-seoulair]

My guy made a recursive object flattening linear complexity algorithm in a react codebase. Insane.

[@AshutoshSingh-we9nf]

Thanks guys, I have been failing at interviews, I have got redirection.

[@JohnVandivier]

love these two guys lol

[@jaredhead9503]

Ben almost laughing the whole time has me dying

[@stephenmount6181]

Is ben tricking Clement into building a new startup masquerading as a technical test? 😱😱😱

[@oliverhughes169]

This is great! But you should probably caveat (make it really obvious) that here you're not following best practices, and are just writing quick code to get something working - just in case newer devs think this is a great example to release to prod!

[@dante_ele]

I like how Ben is gone when the console.log appears

[@MattXChrist]

I love how both of them couldn't get that smirk off their face... especially clement

[@samuelgunter]

I forgot that you can have helper functions *outside* of your React.FC... I've always had them on the inside of the React.FC, but that's inefficient because every instance of the component has to create that callback function upon every render (maybe helped with useCallback), but storing the callbacks outside of the component won't require any duplication. (Like how pre-ES6 classes, we were supposed to add functions to a "class"'s prototype instead of storing the function directly in the class, to reduce duplication)

[@provaprovaprovaaaa9667]

This is more a JS interview than a ReactJS. Only the first question was really about React.

[@tusharpahuja]

One should never use personIdx as a key. If the length of data changes, react would re-render the existing entries as well. A separate property like id should be used which is unique and consistent.

[@abhijithv8403]

🔥🔥🔥🔥

[@benitocamelas7784]

my boy clement going for the lincoln drip

[@lloydmiller4439]

Bro, Clement is a monster. Regular devs would've used reduce, but watching his approach blew my freaking mind.

[@dadestor]

His approach is overly complicated and terrible

[@bonfacenjuguna214]

Over engineering mostly

[@erickbravo5800]

Class components, grooossss.

[@_parassolanki]

We want ben style hard or Advanced react interview..

[@shahzaibriaz6552]

What I'm doing while watching this video like Ben is talking to me and I'm doing exercise on my end (Laptop) Beating Clement :) :D Just enjoying that how much good I'm at React.