Javascript Coding Interview Questions- You Must Know Them

Learn this 5 Javascript coding interview questions that I heard hundred times on Javascript interviews during last 10 years. They are focus on basic javascript knowledge this is why they are being asked so often.
TIMESTAMPS
0:00 Most popular Javascript coding interview questions
0:27 Closures
2:09 Cloning objects
3:59 Count vowels inside a string
8:32 Reverse each word in a sentence
9:25 Most common string
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[@Vivek-Nishad]

Object.assign and spread operator only work it you have a flat object like {a:1, b:2} But if you have nested object like {a:1,b:2,c:{d:3}} it will copy value of a and b but reference of c,d. so, if you want to copy nested objects you can use "structuredClone(obj)" or "JSON.parse(JSON.stringify(obj))"

[@MonsterlessonsAcademy]

You are totally right

[@vishalupadhayay6391]

JSON.parse(JSON.stringify(obj)) will not work if the object has Arrays, Functions, and Date nested within. In such a scenario, we may have to use loadash or write one custom function to handle Arrays, Functions, and Date objects.

[@SuperMatsumoto23]

I am sooo grateful for this video!! I am a junior developer currently preparing for my tech interviews, and some of this stuff was difficult to understand while just reading a text explanation. Thank you for showing these examples step by step, these have helped me get a better understanding of the theory. ♥

[@MonsterlessonsAcademy]

Glato to hear that. For interview preparation you might be interested in my Javascript interview questions course where you learn 56 different topics which fully cover Javascript. monsterlessons-academy.com/courses/javascript-interview-questions-coding-interview/

[@AndreaDragotta]

Regarding the clone example, be aware that these are shallow copies (they do not work correctly when the object contains other objects). If you need a deep copy you should use the new "structuredClone" api or the usual trick with "JSON.parse(JSON.stringify(obj))"

[@MonsterlessonsAcademy]

I have a full video about shallow comparison vs deep comparison. kzbin.info/www/bejne/qJaTeGtvedyCmJosi=snVLRIAqpU0_5OuN

[@joeldaros]

I really like your videos, you get straight to the point. Please make more videos like this one!

[@MonsterlessonsAcademy]

I have now a full course of 59 coding exercises for Javascript interview. monsterlessons-academy.com/courses/javascript-interview-questions-coding-interview

[@clement2814]

Thank you, clear and concise

[@MonsterlessonsAcademy]

Glad it was helpful!

[@jonathanjohnson2785]

I don't have words to fully express my gratitude. Closures, cloning are things I found hard to understand but your style of teaching made everything so simple to understand. Thank you so much and all the best❤👍👍👏

[@MonsterlessonsAcademy]

Wow, thank you!

[@yeti9537]

This is great. Thanks!

[@MonsterlessonsAcademy]

You're welcome!

[@Shivam-sl4sp]

Thank you man !!

[@MonsterlessonsAcademy]

You're welcome!

[@n_fan329]

for the last question..we can also do Object.entries(mapping).sort((a,b)=>a

[@MonsterlessonsAcademy]

Sure there are different solutions to the same problem.

[@bendevweb89]

As a Junior Developer your content helps me a lot to prepare for interviews and improve my logic Thank you very much 👍

[@MonsterlessonsAcademy]

Happy to hear that!

[@mohammadyousuf1567]

I am addicted to your style of teaching .. : )

[@MonsterlessonsAcademy]

Glad to hear that!

[@doniaelfouly4142]

thank you so much

[@MonsterlessonsAcademy]

Welcome 😊

[@orz5516]

In the findVowels i would expect a senior developer would do it with an object because with includes that complexity is much higher. With an object you can just iterate the string once and check each time if the char is a vowel with O(1) complexity

[@MonsterlessonsAcademy]

There are different ways. Object is also not ideal. Regexr is easier that const vowelCount = str => { const regex = /[aeiouAEIOU]/g const s = str.match(regex) return s ? s.length : 0 }

[@orz5516]

@@MonsterlessonsAcademy And thanks for the videos, you are great!

[@damienspectre4231]

For the first problem - I understand closures and you are returning a fucntion within the parent function that returns the secret. but Im curious - why not return the secret string directly instead of within the child function? its a const and its private to the someFn() and cant be modified once declared...

[@MonsterlessonsAcademy]

It was just an example to show closures. environment variables should not be written in code in any case.

[@dmytro-skh]

as for me reduce in the last example is too complicated to understand and debug. Nice for an interview but I would avoid such things in real code. I.e. if jun dev will have to work with that piece of code. In general good video, will look others on the channel too :)

[@keneldridge]

I like Object.keys(counterObject).sort((a,b) => { return a > b ? -1 : 0 })[0]

[@leojohn6702]

Quick question. Currently building my portfolio projects. But I have no knowledge of data structures and algorithms. Should i start training after my portfolio will be completed? Or prior the portfolio?

[@MonsterlessonsAcademy]

Do a portfolio, CV and then improve your knowledge and add it. If you are a junior forget about data structures and algorithms at all. learn language and framework.

[@dragosp.7635]

at 3:50. I see it also work const clone=object. Is it a good practice?

[@MonsterlessonsAcademy]

It is not. You assign the reference to the object and not a new object with a value. Try to change property of clone and check the value of both objects.

[@sliceem88]

Best !

[@MonsterlessonsAcademy]

Thank you!

[@amitkrishna2412]

Hi , Is there a document or a list of such interview questions that you have maintained?which I can follow?

[@MonsterlessonsAcademy]

No I don't have something like this. But I have a full course with 57 Javascript questions which covers all knowledge that you need. monsterlessons-academy.com/courses/javascript-interview-questions-coding-interview

[@OliaYarukhina]

Круто! Дякую! Цікаво звідки Ви, Олександре?)

[@MonsterlessonsAcademy]

Originally Ukraine, last 8 years Germany

[@testify7228]

Hi, For last question To get element which have max occurrence: After creating object, can we use .sort() nd do descending order based on Occurance nd then return first value from sorted object. Is it correct?

[@MonsterlessonsAcademy]

Hi, There are different ways to solve the same task.

[@testify7228]

@@MonsterlessonsAcademy ok dude. Thanks for replay I saw ur 59 interview questions video course, really worth fir spending time in it

[@cryptopinky2355]

Why do we write acc[1] and el[1]? what is the index for and why is it always 1?

[@MonsterlessonsAcademy]

Because there are just 2 elements in the array and we want to work with the second one.

[@jjjj5452]

Now just need to get an interview that asks one of these 5 questions...

[@MonsterlessonsAcademy]

Good luck with that

[@sameoldsteven9571]

cant we solve the last question using Set?

[@MonsterlessonsAcademy]

There are different solutions to the same question

[@AndrewTSq]

The count vowels i just did [...str.toLowerCase().matchAll(/[aeiou]/g)].length not sure it was right, but worked on my examples :) fun questions :)

[@MonsterlessonsAcademy]

It's a totally valid solution. You passed :)