Tricky JavaScript Interview Questions and Answers 

Honestly, I am happy that I found your tutorials. Now I am feeling a little bit comfy so I can prepare for the interview without worries

Thank you, many times on an interview it becomes obvious the interviewer watched these videos too.

this was really helpful. i am using javascript for many years but never knew of so many features like freeze and seal

This man is capable of explaining things well in a simple way, the way few people do. Thank you, sir.

If you want to crack these questions then just ask the interviewer where he has used such scenarios. You'll be instantly selected

Thanks Sir for the videos you make. About removing duplicates, if anyone does not want to use ES6, here is how it should be done in ES5. var a = [1,2,2,3,4]; a.filter(function(value, index) { return (a.indexOf(value) == index) });

For 3:00 question, I think in this solution that works for the input provided: var nums = [1,2,2,3]; nums.splice(2,1); console.log(nums); I know it looks a bit silly but, hey, I got the answer. Obviously, if there is more than one duplicate, then the Set works fine.

This vid was meant to subs both your channels. Thanks a ton!

oh god, i wish i never sit in front of you in a js interview.

Object.freeze ---> Prevent any write operations in that object. Object.seal ---> Able to edit existing data in the object, but not able to add anything new

8:43 - me at my homie house.

2:20 first I just did this let nums = [1, 2, 2, 3]; nums= [1, 2, 3]

Great video. Each question taught me a concept I barely knew. Thanks for this gem !!!

Great class and very well explained. Please keep this channel because I´m sure It has been helped a lot of developers which try learning more each single day like me. Thanks

I've been watching u for a while now, and your didactics (and thumbnails) are the best. Subscribed!

After this one, I had to subscribe.

Reason behind "arguments" not working with arrow functions is that they take the scope of a parent block :3 so it actually shows parent function's arguments

@7:00 thats pretty interesting, and depends on the direction of associativity. < and > (I hope those show up, less than and greater than) have left-to-right associativity. = (equals sign) has right-to-left associativity, which is why we can do a = b = 4 developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence

these questions are so good, they give you a deeper understanding of javascript

These are all code puzzles (not challenges) that an interviewer would use in hopes of eliminating a candidate that they've already decided they don't want but have to appear to give them a fair chance. I would not want to work with a team that codes like that. And I sure wouldn't use their application. It would have a billion bugs.

I wouldn't ask these types of questions in an interview. If anyone wrote code that is so ambiguous, I would question their motives

best explanations in most of the tutorials

The second question would still take O(n) Time and space complexity, not using forloop doesn't mean that you improved it.

for the second problem, you can convert the array to a string, remove the first number 2 with replace() and then split the resulting string back into an array nums.toString().replace(/2,/, "").split(",")

Great video! You're a very good instructor and easy to understand as well.

// Keep in kind that Object.freeze(object) method is a "Shallow Freeze"! let obj = { name: 'Rango', address: { street: '33 eastbound', city: 'Toronto' } } Object.freeze(obj); obj.address.city = 'Montreal'; console.log(obj); // You will see the 'city' has been changed to 'Montreal'. // As, Object.freeze() method is a "Shallow Freeze" which will only protect upto one level deep. Hence, deeply nested Objects within that can still be modified.

Very important tutorial for fresher as well as experience person

The unique values in new array can be achieved by Set object and spread operator as following, const numbers = [1,2,2,3]; let uniqueNumArr = [... new Set(numbers)]; console.log("Unique Array : ", uniqueNumArr);

Day by day am becoming a pro developer watching your videos :)

Thank heaven's for Typescript. There was only one of these I got without thinking

Great teaching! I have been searching this kind of videos for a long time. Thanks.

as "+" behaves as concatenate operator in first console JavaScript automatically converts int 2 to string and concatenate to result into = 22. While in second console log "-" acts as subtraction operator and converts string to integer and results to = 0.

I always try to get Why part of the answer. It makes me better developer and good at what I do at work. Its shame most people watch these tutorials for jobs! not become better.

If we need a revision of JavaScript, we watch your videos and interview questions.. Thank you so much

Dude you killed it ... Thank you so much for the tutorial!!

I have no words to thank you sir.... it's really really very helpful and your explanation is great🙏🙏🙏

Thank you so much for these tricky things! Reallly useful.

You not only taught us interview questions but also how to learn language passionately..!!

Amazing how much I DON'T know, A great way to actually learn Javascript, or any language is to tackle questions like these, Learning New methods is never going to harm you as a programmer. I spent over ten years as a C++ programmer, one day, took an online course and realised I probably only knew about 10% - 20% of the language. Very nice video.

The first problem you mentioned. the actual term used is Type coercion.

Really need to thank you for a great in-depth video , i attended a client interview and i was able to answer it because of this .

This video is a goldmine for a CS freshy

Sir, upload more videos. These videos are extremely useful. You are explaining things that people couldn't find in other tutorials.

Thank you so much for the video... helped me a lot.

good for interview practice in Javascript Frontend

Q2--Remove duplicate from array Ans:- arr2 = [...new Set(arr)];

JazakAllah Aameen 🙏 🤲 😍

you are too good at explaining . how do you do this ! i understand even if it not understandable..........

Sir, you are grand master in JS. Thank you just keep us updating in js. 😊

I'm about to watch every video you have, this is amazing!!

Oh damn this is so tricky, then I think there should be many more tricks to ask these kind of questions. Thanks to Techsith

Hello. Can i say something ? You are the best teacher of JS in the whole WEB :)

If an employee asked me some of these questions in manner of practical application I probably wouldn't want the job.

Dude I love you, please keep these going

Quality content and youtube put restrictions on it. World can't be more unsafe than this.

Great video sir.. Please keep posting such contents

Awesome techsith!! This is very helpful.

Thanks Sir for this video ... it really help us

Thank god u r not my interviewer.... Well I'm a new subscriber.....

Thanks for this amazing video.. I was eagerly waiting for next next questions !!!!

Now I know what to ask incoming interviewees!

as usual awesome video from techsith..keep doing your great job sir.

This is well explained excellent tutorial. In very short time you covered a lot. This is more useful beyond only pass the interviews.

Very useful information!

would I be wrong if I said, " nums.splice(2, 1);" for the 2nd question? you said not to use some methods, I do know which one you meant. this is one line so it should give us the desired result.

Cool video. Thanks for the information!

Thank you so much sir for these fantastic questions this helps me a lot

Very nice video sir. Thanks a lot.

Thank you very much for sharing I really appreciate it.

Thanks, I learnt new methods from this session.

Nice video, just like the past one

I always wonder what is the mindset of interviewer who ask difficult and tricky questions in interview. Is it to show to the interviewee that I (the interviewer) am better than you? That you are joining a "Great" company that will "teach" and "educate" you? These tricky question is a show of my superior intelligence to establish my position of authority? Most of the time, it is exactly this mindset (I have personally have sat among numerous panel of interviewers and being plugged in to their personality knows what is motivating their action). Then the question is why are you employing people who is inferior to you? What are you trying to achieve for the company? Does knowing all the obscure stuffs that majority of interviewee don't know make that one interviewee more superior? Does those obscure stuffs used frequently and critical to the success of the company? Imho, the mindset and attitude of the people you employ is more important that what he knows at the point of interview. Knowledge can be picked up and skill set can be honed. Mindset and attitude however is difficult to mold and tend to persist throughout a person's life. If you employ someone like the interviewer who is fond of asking tricky and difficult question, even though he knows ALOT, your company will never grow beyond the capability of that one interviewer's level because he is not comfortable to admit people who are more capable than him. I personally have lived through all these and I tell you that one interviewer is the biggest stumbling block to the company's growth in capability because no one can be better than him. Those who can successfully answer his tricky and difficult question are rejected while those who cannot, are admitted.

let nums = [1,2,2,3]; let correctway = nums.filter(onlyUnique);

Helpful tutorial thank you

excellent video

Thanks for those amazing videos!!

Sir please make a tutorials on complete nodejs like multar, body parser, jwt, files handling etc

Thanks for the video. It's really helpful.

interviewer from Tech M asked me the same exact question difference between console.log (55)

I don't understand why there're so many haters... Those are actually good and valid tricky questions. Btw sir, you mentioned that you have another channel that teaches algorithm and data structures, where is the link?

Awesome video sir. Thank you

thanks for everything ..a small request they usually interviewer ask ..where you have implemented this in project ,for closure and other things

Not sure I understand why it would compare to -Infinity. It seems like it should see the length of arguments and return the first one if there's just one. If there are more, it should start comparing them to each other. Not sure how -Infinity logic comes into play. If you pass nothing, I'd actually expect it to return Infinity, not the opposite. I'm not sure if the way it works is based off how you do things in math or just a base assumption made by JavaScript authors.

Awesome Sir!!

clearly explained sir. I faced some questions during my interview. Can you please explain them as well? these are the questions: console.log(!![].length); console.log(!!' '); console.log(1+2+"3"+4+5); console.log(1 + true); I have checked the answers but need to know thoroughly the theory behind it.

Thanks a lot of man. Very interesting video.

I loved this video, thanks !!

Thanks a lot techsith!

The job interview cant be hard . Techsith: hey 😊 Me: 😭😭😭

Thank u soo much sir The way you explain all the questions is 1337(elite)

Very cool stuff!

Superb. Thanks Sir. Can you please do a video on typescript and es6 interview questions?

Amazing content..! Question: Whats the difference between object.freeze and const?

great info, I learn I lot from this.

brilliant.....thanks a lot.... you are amazing !!!

Hi sir I'm biggest fan of your tutorial. Its helping us too lot to gain our knowledge. I have a doubt sir can please explain how to skip a single num from an array for example if array a[1,2,3,4,5,6] and from this if i want to skip the 3 and show remain. Thank you sir.

time 11:45 can't we declare profile as const, instead using freeze?

You are great. Hats off.

a good set of questions well explained ty @techsith

Thank you! amazing