What kind of interview questions to expect in JS?

Question

JavaScript

Hello, I'm about to interview for a frontend position. They said that answers to all questions can be found in the first part of Ilya Kantor's textbook https://learn.javascript.ru/?map
I would like to ask you, perhaps you know a selection of the most tricky js questions? Thank you.

Answer 1

For fun, I bookmark all sorts of js questions:
https://habrahabr.ru/post/231071/
https://medium.com/@sapy/7-interview-questions-and...
https://habrahabr .ru/post/239065/
https://github.com/h5bp/Front-end-Developer-Interv...
perfectionkills.com/javascript-quiz
But, without a good knowledge of the language, it is very difficult to give adequate answers to many questions.
There is also a separate file in which I store questions that were personally asked to me at social security and I did not know them. I advise you to get the same one. Useful in the future)

Answer 2

"Well, admit it already - did you debug Javascript with alerts?" (c)

Answer 3

Tricky questions, you say?
1. Which of the es6 innovations is fundamentally not polyfilled in es5? Why? (And why the hell do you need it, after all). (And at the same time, I would ask to follow up with a polyfill of some of the features, for example, this in the arrow function).
2. What conditions must be met in order for v8 to compile a function to native code? Well, of course, why?
3. Why up to and including es5.1 typeof null === "object"?
4. What will actually happen if you write

const arr = [];
arr[3484] = 5;

5. An analogue of the second question, but still: what, in your opinion, could be associated with a bug in one of the versions of chrome, leading to the following result:

function foo() {
    return typeof null === 'undefined';
}
for(var i = 0; i < 1000; i++) console.log(foo());

>>> 121 false
>>> 879 true

6. What ways do you know to make js perform several operations at the same time (literally, per clock)?
7. Will documenty.onready work if the script is loaded with the async attribute? In what cases and when exactly will it work?
8. What can and cannot be done in the document.beforeunload event?
But, in fairness, these questions are not even for the middle, some of them are not so much tricky as stubborn, and if you are asked them, you should think about the adequacy of the company.

Answer 4

Looking for a job as a front-end developer in 2016

Answer 5

Surely they will ask about closures, call context and prototype inheritance.

Answer 6

At interviews, we ask questions for the horizon, for example, here is a list of topics that a developer should have an idea about, it is absolutely fair and approximately the same as ours: https://www.smashingmagazine.com/2016/11/not-an-im ...
From a junior, of course, we do not expect him to rummage around in everything, but juniors, like the rest, are driven hard by css (for many, even with extensive experience, there is a huge gap there).
But we call to talk only after we looked at the code and we already more or less liked the way the person writes.

Answer 7

We have a collection of questions , among which there are questions about JavaScript and some JS frameworks.

Answer 8

Read up on how " Hosting " works if you don't already know.
Understand how setTimeout() works and read about what a Call Stack is .
If you have time, read about existing development patterns (JS Design Patterns). For example, Factory, PubSub/Observer, Singleton.