r/FullStack

Today I had my first technical interview after around 3.5 years, and honestly, it hit me harder than I expected.

I’ve been working mainly as a frontend engineer with React and also have experience working across backend/full-stack systems. Over the last few weeks, I’ve been revising React, JavaScript, frontend architecture, Node.js, databases, system design, etc.

I went into the interview feeling pretty confident.

The interview started with:

- What is REST?
- Design an API
- React reconciliation
- JSX
- Infinite scrolling / frontend design

The part that really got me was the React reconciliation question.

The interviewer gave me a Todo-list-like example using index as a key, with items being added at the beginning/end of the list.

I understood that something was wrong with using index as a key, but it took me a while to reason through exactly what React was doing during reconciliation.

He eventually gave me a hint about reconciliation, and then I was able to connect the dots.

Then I got another question:

"Why does JSX require a single parent/root element?"

I could identify the issue in the code, but I couldn't clearly explain why JSX requires a single root.

I also got an infinite-scroll design question, which I was relatively comfortable with.

The weird part is that after the interview, I realized:

I actually knew most of the concepts.

My problem was being able to retrieve and explain the fundamentals clearly under interview pressure.

For example, today I started revisiting basic JavaScript concepts like:

- Scope
- Hoisting
- TDZ
- Execution context
- Scope chain
- Shadowing
- Closures

And I realized I can understand these concepts when I reason through them, but explaining them cleanly in an interview is a completely different skill.

So I'm curious about other experienced engineers:

Have you ever had this experience where you knew the technology fairly well, but an interviewer exposed gaps in your fundamentals or your ability to explain them?

How did you fix it?

Did you:

1. Go back and systematically revise fundamentals?
2. Do mock interviews?
3. Practice explaining concepts out loud?
4. Focus more on problem-solving rather than memorizing interview questions?

I'm especially interested in hearing from 5–10+ YOE engineers who went through something similar.

Today definitely humbled me, but I'm trying to use it as a diagnostic rather than letting one interview define my confidence.

Would love to hear how you guys handled this.

I always find it a little ironic when a company offers web development services, but a simple scan of their own website gives them an F for security.

Especially when many security best practices are quick and easy to implement. They should be a standard part of development, not an option.

Security is part of building a good product.

I thought I'd get into backend development, and since i know python pretty well i could learn django. But nodejs and the whole javascript just seems to be more in demand, and i dont know what to exactly do right now. i want to develop a skill as fast as i can, because i currently dont have the time to learn something like javascript from scratch. but if its worth it, i dont mind giving it my all and learn the Java framework instead.

i just dont want to be in a situation at the end that i know neither properly and end up wasting time

Hi everyone, I’m currently focusing on NestJS/Node.js backend development and want to learn frontend as well.
Since I already know NestJS, which frontend technology would you recommend learning next?
React, Next.js, Vue, or something else?
My goal is to become a stronger full-stack developer while keeping backend/NestJS as my main focus.
Thanks!

Hello guys i am currently learning react from a yt course called chai aur react so how to learn after finishing this, what projects to makee and should i also go through the react docs and how many days should i give more to react before starting backend pls give some genuine help

I'm currently learning full-stack development and I'm about to start learning backend. Right now, I only use AI manually, mostly copy-pasting my code into ChatGPT to help me understand or fix things.

I'm really interested in AI agents, but I don't want to rush into them before I have a decent foundation. I'm also a little worried about falling behind.

So my question is, how do I know when I'm ready to start using AI agents to make my development process easier? I have a feeling they'll be really useful once I have a solid foundation. And when I am ready, where should I actually start?

For context, this is currently just a hobby for me. I only code in my free time, but if I eventually become good enough, I'd like to take it more seriously. So I'd also appreciate any advice on what I should focus on for now and what I can leave for later.

I have been thing what should I choose for backend as i want to become a full stack engineer. I just completed js and React in frontend . I am confused between java+spring boot or .Net . I will learn python as well .

What's your opinion ? What will be better option for me ?

Where can i deploy my project back and front end for free for my scool project

I'm learning and trying to understand each line of code like how it works ,why its necessary and workflow but after realized if nowadays AI not gonna drop in future why I'm learning all this stuff if a non tech 12 yr boy can do this

For developers who have transitioned from frontend to full-stack/.NET, what backend concepts would you recommend prioritizing to become job-ready?

There are many stacks in the full stack thing like lets say mean stack , mern stack , pern stack like there are many things. Every day a new stack is getting updated and a new stack is trending so how to stick on one thing ?

I’m currently learning full-stack development and using React with Tailwind. I understand a little bit of TypeScript, but I’ve never actually built a real project with it.

I don’t know what project I should build because I can’t seem to find any project-based tutorials using React with TypeScript.

The more I search, the more things I find, like Next.js (which I’ve heard can also be used for the backend), Express.js, databases, etc. I also don’t know when I’m supposed to be ready to start learning backend.

At this point, I’m pretty confused about what I should actually focus on. Should I stick with React + TypeScript and build projects first, or start learning Next.js/backend?

I’d really appreciate any advice or recommendations you can give, especially YouTube tutorials (I prefer project-based ones). Any advice on what I should learn next would be really helpful.

hello,everyone i am a 16 year old teeanage,living in pakistan.I am thinking to learn MERN form DigiSkills (a platform convinced by govermnet to enpower youth) i am thining to learn mern form it.The mentor acctually is top rated at upwork.In the end i will get a certificate also.What do you think.Does it help me in career and future and should i learn it.

I am going to start my 1st year in btech cse from next month . So I started learning web development and made todo_list website using HTML , Tailwind CSS and React ,

https://to-do-olive-pi-99.vercel.app/

Now , I am stuck on what to make next

I want to know all of your's advise for my next project,plz recommend me so that i can upskill my self

As i am learning Fullstack and react and learned some basics, it is only matter of time and practice. So i want you guys to give me some mini projects to master. If i will get some problem i will comment for help. 👍

I just started The Odin Project. I need advice from seniors should i focus on finishing it or do something else too. I wanna be a fullstack developer.

Stay away if you're goin to say web dev is dead or ai is taking over. I just need advice on the roadmap and resources

Global Objec,t Modules and Require File System, Streams and Buffers, Client & Server, Request & Response, HTML Response & Status Code, NPM & Dependencies, Express Apps, Middlewares, Route Params, Query Params, Post Request, Put Request , Patch & Delete Request ,getById Middleware II

started learning node js and express js and i listed the topics that i covered above. what are all the things that i need to learn before starting out with db and what should i learn in mongo db.

Hi, I'm a software developer with 6 years of experience and unfortunately my current organization isn't performing well. I need to shift to a better place. I'm planning the interview prep but I've been mostly an Angular developer. But in a new role they might expect me to understand the whole system in the current market. Though I don't have hands-on experience in deciding the system architecture of the backend would it be good to stay making projects to fill this gap or just say full stack developer with 70:30 frontend end backend. I'm so puzzled. Any senior developers or tech managers of you help me. It would be of great help. I'm an introvert and have no friends and I'm not sure what's happening in the job market right now.

Thank you

Hi all, 'm a self-taught frontend developer currently learning Python, aiming to add a specialization on top of my existing skills. Torn between:

• Backend development + AI/LLM integration
• Machine Learning Engineering (math-heavy, model training)
• Cybersecurity
• Cloud/DevOps

My constraints:

• ~9 months to learn, starting from where I am now (solid JS/React, developing Python/OOP fundamentals)
• Want to be realistically employable within that window
• Not overly saturated, but I know difficulty isn't a dealbreaker for me — I'm consistent and willing to put in real hours
• No CS degree

Would love to hear from people actually working in these fields: what would you actually recommend for someone in my position, and why?