REAL React Interview Questions

Ever wondered what you'll be asked in front-end engineer/React interviews?!

This video is to give an idea of what you questions could reasonably expect from a React developer hiring process.

Many of these questions are approximations of what I think you could expect as an entry-level software engineer, or the types of things I would ask if I were coming up with topics from scratch. They all offer opportunities to show off your knowledge, even if they seem basic on the surface.

Let me know if you find them helpful!

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Who am I?

[PeterElbaum]

Are these questions helpful to you? What React questions have you encountered in your interviews? Let me know!

[chrisdietrich]

Could you make 40 more of these exact videos? Perfect to prepare for interviews

[tempgrey]

1.What is JSX? => syn. sugar of createElement
2.what class named as classname in react? => class is reserved in JS
3. Describe DataFlow in the React? => Unidirectional
4.How would you delay API Call untill component is mounted? => useEffect Hook
5. Should you use ternary or && operator to conditionally render React components? use ternary operator (&& have falsy thing)

[y-yyy]

Thank you so much! I was watching your video before my interview and I actually got asked the jsx question. I kinda knew it already, but, having researched it more thoroughly after this video, I was even more confident answering it. Really appreciate your help!

[HenryBelcaster]

Was saving this for when I became ~technical~. Awesome stuff, Peter 👏

[srinivasnahak]

Thanks so much for all these basic looking yet tricky questions

[berniezhong]

This video was super helpful I never thought about whether or not the ternary or && operator would be better, since I usually use ternary but your response was definitely a huge plus to know

[kashmirtechtv]

One of the best. And yes these are the questions that are asked mostly especially Use Effect

[ankitalath]

Great questions, and I like how to you explain the area where to shine. I would encourage to please create more React or Angular questions like these. Amazing, thanks a lot.

[karthikeyans]

This was really eye opening. Keep up the great content!

[ekaterinalukyanets]

Thanks for a great video!

I was putting it on pause, thinking about the way I’d answer and the resuming the video.

The question about the ternary operator and && I wound answer in the following way:

“You should consider the reasons why you are about to use conditional rendering.

If the reason is that assuming a particular condition is met you display a component, if not, nothing is displayed instead, use && operator (and handle it with care 😌).

If you are considering displaying either one component OR the other, use ternary operator.
The caveat in here: keep in mind react reconciliation algorithm. If components are of different type, React will unmount the whole component’s tree and the state (which you potentially need) will be lost.
Plus it’s always more costly operation then just changing an attribute. So consider further examining the case, maybe you just need to change some attributes instead in the same component.”

[Srishti]

Thank you, that was a great, concise video!

[phead]

The className thing has nothing to do with the class being reserved syntax as it's working just fine in Preact.

[viktorricchiuto]

You can also Cast the length to a Boolean before using the && operator to fix the issue of a zero being rendered

[birukamare]

Very helpful. Thank you! I appreciate if you talk about common mistakes programmers make when using react just like the && operator you mentioned in this video.

[rincyphilip]

nullish operator can be used instead of ternary operator because only if null or undefined is considered as false on the life hand side,

[VolodymyrDovbenko]

Regarding point #5: that's why we need to use double inversion in such cases, which casts the value into boolean: !!items.length && ...

[danielkamau]

Didn't know about this ternary and &&, now I know. Thanks Peter.

[m.k.mubarak]

Hello sir. I am just starting my career and am preparing for my first interview as a mern stack developer. I came across your interview playlist.... And it seems just made for me.. thank you sir.. and yeah.. you won a subscriber 😅

[wudao]

Thanks, great video. What's are some of the shibboleths of an amateur with react?