JavaScript Interview questions everyone gets wrong
Ғылым және технология
In this video I’m going over MORE JavaScript interview questions that you might encounter in your software developer interviews. This video will feature questions that really test your understanding of common pitfalls and weird parts of JavaScript, such as “this” keyword and scope chain.
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Пікірлер: 61
The correct answer to all of these: it won’t pass code review.
Have an interview tomorrow and have been binge watching all your videos
@catherinelijs
8 ай бұрын
Thank you! I hope you got it!
@LucianoClassicalGuitar
Ай бұрын
How did it go lol
Binging all of these videos now that I am expecting some tech interviews. This is also great insight! I wish I was looking these up BEFORE when I was giving interviews. Thanks!
Really love these old school questions ❤ Everyone should know this
Thank you for this video. Much needed :) .
Thank you for the tips 😊
I like it somuch.... kindly do more vdo based questions on javascript function
Do they really still ask questions including var ? I literally NEVER use var
@6-dpegasus425
Жыл бұрын
Same I only ever use let or const
@MrChicano101
8 ай бұрын
Yea
These are definitely good academic things to know to understand some of Javascript's history and design philosophy, but any company actually asking me this many questions about my understanding of "this" and "var" would make my really wary of moving forward. This would indicate to me that first, the company might still be using var in practice which for all intents and purposes is almost always the worst option to use for instantiation, and that second the company might be using JS for OOP, which would indicate to me a big mistake, as JS really shines now with a functional focus and there are much better languages to use for OOP. I will concede though its important to understand the context of the arrow function vs a functional declaration. I would say much more important and likely questions to get in a modern JS interview, relate to especially closures, first-class functions, and might even touch on typing with TS.
Wow, super straightforward thanks Catherine!
@catherinelijs
Ай бұрын
Thanks!
I specifically search for your videos lol. they have helped me previously in my interviews alot. Thanks alot Chatherine 🙌
@catherinelijs
Ай бұрын
Thank you! I have lots more content ready so I'm really hoping it will be helpful!
It's crazy to me that after 4 years of uni, now that I am lookinf for a new job, I am looking at this vids to prepare for interview. Most concepts aren't really used at all in real life and thus things get forgotten. Makes you question the real use of these questions xD Anyways thanks for the great vid
@catherinelijs
Ай бұрын
Thank you and you got this! Were you able to find a job in the past 2 months?
How common are questions regarding var vs let and arrow funcs vs normal funcs? I started learning JS self taught around June of 2022 so almost everything I’ve learned and built has been with the latest syntax. Would you recommend learning more about pre-es6 topics solely to prep for interviews?
@catherinelijs
Жыл бұрын
Your main focus should be ES6 and modern JS and frameworks. That’s where we’re all headed. For older tech companies you can look at pre-es6 topics but that’s a lower priority imo
@MehdiGlz
Жыл бұрын
Hey Costco Membership, I know this is an old comment, but for anyone out there: ime this is important to know for interviews. Last year I did a ton of interviews and these questions came up more than once, both at small companies with old stacks and big international consulting companies. So it's good to study up before interviews
Thanks i never really understood arrow functions but this helps
@catherinelijs
5 ай бұрын
Happy to help!
So helpful!
@catherinelijs
7 ай бұрын
Thanks so much!
Thank you so much
You better than my teacher 😂
Some of these questions appear to be made before linters existed and its a wonder they keep being asked
canadian confirmed, lol. also...on the first one, i've been doing python the past 2 months and i'm going to be ruined when i get back to JS...now to watch the rest of this video
in the last question, b++ of inner() is incrementing var b = 2 of outer(), correct? (This is a closure, yes?)
@petrkavulok9753
Жыл бұрын
Hi Harold, it is not. in this case it appears as the line 5 is ignored completely and the console logs only line 6 in an unchanged form. To get a better understanding, look up JavaScript Hoisting. Cheers
@myPrzeslaw
3 сағат бұрын
@@petrkavulok9753 Well, line 5 isn't ignored, it assigns NaN value to local b var (as NaN is valid result of incrementing undefined in js). But that value isn't logged and is overwritten in line 6 by the value 3.
@myPrzeslaw
3 сағат бұрын
No. It would be a closure if line 6 did't existed (or existed without 'var' keyword). Once you declare var x anywhere in the function (even in its last line) THE WHOLE SCOPE OF FUNCTION don't have access to outer scope var x at ANY LINE (even BEFORE initialization).
The more I watch these vids, the more I cringe at my prior confidence in JavaScript
The second example, console.log(x) would actually return 21 instead of undefined. Yes variable x is hoisted, but code runs from line 1 and below. So if girl() is invoked, that means at that point x is initialized with the value of 21. (if you try in your browser)
@tunacant9106
Жыл бұрын
Nah, it would be undefined, because inside the girl function, x is undefined.
@vivekcse1
8 ай бұрын
@@tunacant9106 On Mac, it gave me 21. Let me try it on PC.
@vivekcse1
8 ай бұрын
On windows also it's giving me 21. So this girl's premise is false. This is like a closure. But the higher order function being non-existent, global scope is taking over.
@agmonblynkos
8 ай бұрын
@@vivekcse1the real reason it logs 21 is because var is also adding the variable to the window, which is where the console.log takes the result from. Try with let or const, it will log undefined
@myPrzeslaw
3 сағат бұрын
It's not. JS hoisting is performed before running the code. It means interpreter firstly moves all the local vars declarations to the top of the scope (but leaves initializations in its original line). The only way var x still has its value from higher scope it has to not be declared ANYWHERE inside girl-scope.
Can I Wait for your INTERESTING front-end web devlopment course?
LOL i have 3 years of experience and the first one got me haha
I prefer to use "const" if possible, then "let" and avoid "var" due to the strange behaviours it causes
@myPrzeslaw
3 сағат бұрын
And it's great and modern approach but if company you applying to also maintains some pre ES6 code it is valid approach to examine candidates it that regard.
You are like a god
Well. I'd have failed... I haven't invested much time into var. It's throwing me off quite badly.
The answer for the last question is Nan ;)
@myPrzeslaw
3 сағат бұрын
No, NaN indeed is the result of incrementation in line 5 but it is not console logged. Console logs the result of assignment from line 6.
😍
const happy = new Year('🌟')
@catherinelijs
Жыл бұрын
Same to you! All the best in 2023
Thank you and you are so beautiful
Mam how much do you earn as a software engineer? Plz reply. Thanks a lot.
If only JS and browsers didn't suck, interviewers wouldn't have the chance to ask us these useless stupid questions. In the question about `setTimeout`, it's not because it's asyncronous but because browsers copy references instead of values.
@myPrzeslaw
3 сағат бұрын
I don't think working as a JS dev is anyhow mandatory. But if you intend to do, it's pretty important to understand how do closures work.
Welcome back Catherine :) do you has twitter?
@catherinelijs
Жыл бұрын
Thanks! I’m setting up new social media accounts and will post the links on this channel soon
always. add. semicolons.
@user-nx5kz9nm7c
Күн бұрын
always; add; semicolons;
This video is gold. 🪙 Thank you for your content!
@catherinelijs
Жыл бұрын
Thank you!