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All front end Interview questions asked during my recent job hunt.

Abhijeet Yadav on August 04, 2020

Interview questions for front end This readme is a compilation of all the question asked during my recent COVID-19 job hunt. I've also att...
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ogrotten profile image
ogrotten •

This list of problems to solve is extremely discouraging. I've done Hackerrank/leetcode/codesignal challenges, and most of these seem like things that would take me at least a couple hours. Mainly, I can't even see a 'first step' to a solution after reading the problem. But if you have all these exercises, it means you had all these interviews without being hired... and if they didn't hire you, then what gnats chance in hell do i have?

Congratulations, truly, for getting the interviews, and I thank you kindly for posting these in an attempt to help others learn from your experience.

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jmmendez profile image
John Mendez • • Edited

These interview questions aren't necessarily meant to be answered on the spot. They're purposely complex so that the interviewer can see your thought and team process.

I was dumbfounded by many interview questions and I'm currently in a few final rounds. One of them is a fortune 500 company, and that's the one I most shaky in and never wrote a full implementation. But by talking my way through it aloud, the interviewer realized that I knew what I was doing and needed more time.

Just make sure to collaborate with the interviewer as if you already work there. Ask questions and provide input as you search for the solution. Understand why you're making certain choices, and the tradeoffs of them. They want to know how you'll be on the job after all.

Any honest developer would agree that if you haven't seen these problems before, it would take more than a couple of hours.

Like, who seriously believes promises were implemented in a day, let alone a couple of hours? And for those who do think that, do you even want to work with that toxic mentality?

The path to the solution is more important than the solution. So focus less on interviewing, and more on acting the same as you would on the job.

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ogrotten profile image
ogrotten • • Edited

Solid take and advice. Thanks.

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devabhijeet profile image
Abhijeet Yadav • • Edited

Yeah, I know right. It's not like I had it all figured out. The solutions I have posted here are the final ones that I had reached after making countless mistake and a ton of console logs. The toughest amongst them were 1 and 7. On any other day I wouldn't be struggling that much but presenting solution during interview is a whole different ball game.

Also I had cleared a lot of interviews but most of it didn't materialize. Some of the interviews I gave were only to gain experience, even when I was not interested in the company I was getting interviewed at.

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asiraky profile image
asiraky •

I disagree. These questions are not that hard for someone calling themself a software engineer.

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ogrotten profile image
ogrotten •

Very helpful. Congratulations on your new title.

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asiraky profile image
asiraky •

A tad unnecessary. Just stating my opinion.

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rohanhacker profile image
रोहन मल्होत्रा •

Your promise implementation is incorrect.
This is how the promise works:
If the handler function:

  • returns a value, the promise returned by then gets resolved with the returned value as its value.
  • doesn't return anything, the promise returned by then gets resolved with an undefined value.
  • throws an error, the promise returned by then gets rejected with the thrown error as its value.
  • returns an already fulfilled promise, the promise returned by then gets fulfilled with that promise's value as its value.
  • returns an already rejected promise, the promise returned by then gets rejected with that promise's value as its value.
  • returns another pending promise object, the resolution/rejection of the promise returned by then will be subsequent to the resolution/rejection of the promise returned by the handler. Also, the resolved value of the promise returned by then will be the same as the resolved value of the promise returned by the handler.
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devabhijeet profile image
Abhijeet Yadav •

The implementation is a rough idea.

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vibhanshu909 profile image
vibhanshu pandey •

I believe it's better to provide a correct solution or no solution at all, otherwise, it may mislead our fellow developers into believing it to be the correct solution. You may check out this link for a detailed implementation and explanation of promises. By the way great post. :)

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devabhijeet profile image
Abhijeet Yadav •

Please read the note before the answer started.

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vibhanshu909 profile image
vibhanshu pandey •

Yes, I've read that, it says "not production ready", not that the provided solutions are psudo-code. Anyway great stuff 👍.

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constantiner profile image
Konstantin Kovalev •

2) Create a promise from scratch

Sorry, but your promise implementation is wrong. then and catch must return new Promise instance but not this. That's why your sample doesn't work correct:

promise
  .then(function(response){
    console.log(response);
  return [...response];
  }).
then(response => {
  console.log(response);
})
  .catch(function(error){
    console.log(error)
  });

Compare results using original Promise.

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kalbrecht_fr profile image
Kevin ALBRECHT •

Hi, thank you for sharing this but can you explain your getHashCode implementation ?
I though you would compute some values, based on charCodeAt() and maybe bitwise operation or anything, to make it unique, but you simply returned the string instance.

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devabhijeet profile image
Abhijeet Yadav •

I expected the same when the interviewer asked the question. However, on further follow up the interviewer asked me to only make a method by the same name available on the instance. Strange 😕

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kalbrecht_fr profile image
Kevin ALBRECHT •

Oh ok weird, thank you.
great blogpost anyway :)

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svinayaka profile image
Siddhi Vinayaka •

For Sum of three,

function sum(ary, target) {
    let right = ary.length - 1;
    let matchList = [];
    ary.forEach((val, id) => {
        let match = {index: null, value: null}
        for (let j = 0; j < ary.length; j++) {
            if (id === j) { continue; } 
            else {
                if (id >= right) { break; }; 
                total = val + ary[j] + ary[right];
                if (total === target) {
                    match.index = `${id} + ${j} + ${right}`;
                    match.value = `${val} + ${ary[j]} + ${ary[right]}`;
                    matchList.push(match);
                }

            }
        }
    right--; 
    });
    return matchList;
}
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bobgravity1 profile image
bobgravity1 • • Edited

lol. here i am a year into learning JS about an hour a day just mainly for fun. got more serious recently about trying for an entry level front end job and have been applying about 3 hours a day. but after seeing this im crushed... yay! thanks for sharing lol

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_ezell_ profile image
Ezell Frazier •

Absolute insanity.

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kurtyazdizadeh profile image
kurtyazdizadeh •

What types of positions did you apply for? Entry-level? Junior? Mid? Senior level? Just curious!

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devabhijeet profile image
Abhijeet Yadav •

It was Software Engineer III position.

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joshuajrodrigues profile image
Joshua •

That makes sense

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rakeshraih profile image
rakeshraih •

Children.prototype = new Parent(), shoudn't this be
Children.prototype = Object.create(Parent.prototype); instead of creating new instance?

Thanks for posting, good stuff.

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mlee0330 profile image
Michael Lee •

Why does 'two' > 'three' evaluate to true?

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devabhijeet profile image
Abhijeet Yadav • • Edited

For this case, ASCII value of first character from both string are compared. Since the first char is 't' from both string, the resultant ASCII value will also be same. The evaluation then moves to the second character of both string.

Character 'w' from string one has ASCII value greater than ASCII value of character 'h' from string two, hence evaluation will now be of below state...

ASCII(w) > ASCII(h) => true
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Also the below evaluates to false

'tWo' > 'three' //false
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zhuangyin8 profile image
zhuang •

11) Convert class based inheritance code given below to ES5 code.
"class Parent(name){ " is wrong.
should be "class Parent { "

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Pankaj Jaiswal •

All this stuff for Frontend post? I am a fresher starting career in Frontend Development. But I hate DSA from my bottom of the heart. What should I do? These types of questions will freak me out.

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Abhijeet Yadav •

I am not sure if a fresher will be subjected to same questions. However, learning DSA will help you out in long term if you are considering Software development for profession. You can check my Resources for preparation blog. It has links to some youtube channel to get started with DSA.

 
asiraky profile image
asiraky •

Never mind how little sense that makes, the author actually stated he was being interviewed for a Software Engineer position. How is the tag of the post relevant, given that fact.

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bobgravity1 profile image
bobgravity1 •

is this type of stuff way beyond a junior front end web dev interview? i f****in hope so lol... i would NEVER be able to answer this

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moniv9 profile image
Mohit Verma •

To prepare for frontend/javascript interview. You can look at this ebook I created with collections of commonly asked frontend questions with solution.

mohit8.gumroad.com/l/ygass