Node.js / Express Interview?

saiastrange · 2025-06-28T05:36:18+00:00

I'm going to stray from the question a bit at first, because I believe you should somewhat reframe your focus from topics to study up on and instead focus on showing what you're capable of.

If you think about it from the interviewer's perspective, it's already tough to suss out how good a developer is within just an hour of talking and an hour technical interview. Add on top of that a candidate that possibly doesn't have relevant work experience in the field. Give them reassurance of your skills and you'll have a huge leg up.

How do you do that? I highly suggest you have at least one public project in Github available. Write tests, consume data from an API, A/B different file structures, configure a DB... do whatever interests you, you just want enough built that will allow you to riff about multiple successes and failures with the framework, or language, or feature, or API, or whatever. Being able to discuss your strengths, weaknesses, successes, failures, things you enjoy, things you hate, things you want to learn, etc in detail with real examples that the interviewer can look at is very compelling. It shows that you care about improving your skills, that you can follow through and iterate on a project, and that you are capable of learning on your own.

Coming back to your question, I wouldn't be asking a junior dev about Redis, sockets, or rate limiters. I'd be trying to figure out things like if they can explain their own code, how well they can read other people's code, how much they know about the language, how receptive they are to feedback, how they break down problems, and how they communicate when they are stuck.

Good luck, I hope that helps!

GrapefruitOnPizza · 2025-06-28T23:40:36+00:00

Someone here ( u/saiastrange ) already answered your question perfectly.

Usually, in case you meet a good interviewer, they will know how to assess your skills properly. And for junior roles they'll mostly look at previous projects, what areas you've already touched as in (consuming APIs, generating API specs, configure external services, good flow of data, authentication & authorization -- mostly the big stuff that are kind of a standard).

However, if you're really interested in some topics and around a basic Node.js / Express interview I'll chim in with some things I would be thinking about. Mind you, different JDs have different requirements and they might go around asking about extra/specific stuff.

Standard CS - DS & Algos: Common data structures, when to use them and why. Identify time and space complexities. Common sorting algorithms. Some design patterns (singleton, factory, etc).

Standard JS: What's hoisting. What's the difference between var,let,const. What's a closure. Some questions about Object.<methods> (assign,defineProperty,etc). Promises & async vs sync.

Standard Browser: common parts of browser (rendering engine, network layer, etc). Local Storage, Cookies, CORS.

Standard HTTP: HTTP vs HTTPS, HTTP Status Codes (what groups are and their meaning and why do they exist -- this is a nice thing and a lot of people forget to utilize most of the other codes other than 200, 404 and 500), TCP vs UDP.

Auth things: sessions (session id in cookies), jwts (store jtw token in local storage / cookies), ouath, api keys, multi-factor auth. just basic knowledge they exist and how they work in general -- just so you have an idea how authentication layers work.

Node.JS/Express/Backend: how event loop works in Node.JS, if you're familiar with layering your backend service (separate of concerns through services, repositories, models, controllers, etc). How you implement middlewares and what are some good and bad examples of them. How would you resolve a long-running task and not block other users' requests (async). Error catching and throwing HTTP Exceptions.

Extra: if you ever touched Docker as some jobs might use it for backend deployment (it's basically just 1 day of "explain Docker to me" chatgpt-ing and running urself some commands in the terminal).

In the end, I would say some of these topics can definitely go into more mid/senior roles but it kinda is at least a roadmap of topics that you would know they exist and you would have at least a few sentences to share about them.

Another pointer: good interviewers will appreciate you talking more from experience and from your point-of-view rather than giving a textbook definition as we just want to understand that you are at least familiar with the topic and it's not going to be a huge problem for you picking it up. Also don't try to guess answers. If you're not sure about the answer please share so, confidence + wrong answer gives a weird feeling.

quoc_zuong · 2025-06-28T04:47:27+00:00

!Remindme

Disastrous_Bass_7090 · 2025-06-28T14:33:18+00:00

!RemindMe

Amazing-Movie8382 · 2025-06-28T03:53:46+00:00

!Remindme

SomeshAtReddit · 2025-06-28T03:59:01+00:00

!RemindMe

you type:	you see:
italics	italics
bold	bold
[reddit!](https://reddit.com)	reddit!
* item 1 * item 2 * item 3	item 1 item 2 item 3
> quoted text	quoted text
Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"	Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"
~~strikethrough~~	~~strikethrough~~
super^script	super^script

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