Mohsen Fallahnejad - DEV Community

Mohsen Fallahnejad

Nov 14

XSS vs CSRF: Two Browser Attacks With Two Different Fixes

#xss #csrf #security #cookies

6 min read

Mohsen Fallahnejad

Nov 13

A Philosophy of Software Design Summary: Deep Modules Beat Small Ones

#books #softwaredesign #architecture #cleancode

7 min read

Mohsen Fallahnejad

Nov 13

How V8 Makes JavaScript Fast: Ignition, Sparkplug, Maglev and TurboFan

#javascript #v8 #performance #jit

6 min read

Mohsen Fallahnejad

Nov 13

React Server Components vs 'use client': What Actually Ships to the Browser

#react #nextjs #servercomponents #useclient

6 min read

Mohsen Fallahnejad

Nov 13

Why React Needs key: The Bug That Moves Your Input to the Wrong Row

#react #keys #reconciliation #lists

5 min read

Mohsen Fallahnejad

Nov 11

Packed vs Holey Arrays in V8: Why new Array(n) Makes Spread 4x Slower

#javascript #v8 #performance #arrays

6 min read

Mohsen Fallahnejad

Nov 11

Next.js use cache, cacheLife and cacheTag: How One View Counter Rebuilt Every Page

#nextjs #approuter #caching #usecache

2

6 min read

Mohsen Fallahnejad

Nov 10

How 'this' Works in JavaScript: Decided by the Call, Not the Code

#javascript #this #functions #arrowfunctions

1

3 min read

Mohsen Fallahnejad

Nov 10

What Is Turbopack? How Next.js's Rust Bundler Avoids Doing Work Twice

#nextjs #turbopack #bundler #rust

4 min read

Mohsen Fallahnejad

Nov 10

turbopackRustReactCompiler: Running the React Compiler in Rust Inside Next.js

#nextjs #react #reactcompiler #turbopack

4 min read

Mohsen Fallahnejad

Nov 10

Bun vs npm, Yarn, Vite and Webpack: Who Does What in a JavaScript Kitchen

#bunjs #npm #yarn #vite

5 min read

Mohsen Fallahnejad

Nov 10

JavaScript Classes Are Functions in a Costume (and What this.constructor Points To)

#javascript #classes #this #prototypes

3 min read

Mohsen Fallahnejad

Nov 10

How SSR Works in React and Next.js: Built on the Server, Wired Up in the Browser

#nextjs #react #ssr #hydration

1

5 min read

Mohsen Fallahnejad

Nov 10

How Next.js Turns JSX and TypeScript Into Plain JavaScript

#nextjs #react #jsx #typescript

4 min read

Mohsen Fallahnejad

Nov 7

"Your Code Is Sloppy" Isn't Feedback. A Link to Line 42 Is.

#career #feedback #codereview #teamwork

6 min read

Mohsen Fallahnejad

Nov 6

AI Is Your Junior Developer. Your Product Still Needs a Senior.

#ai #aicoding #codereview #observability

16 min read

Mohsen Fallahnejad

Nov 6

Start Learning From the Docs. Then Find Your Own Way.

#learning #documentation #career #nextjs

8 min read

Mohsen Fallahnejad

Nov 6

Sliced Strings in V8: How a 20-Character ID Keeps 1 MB Alive

#javascript #v8 #node #performance

4 min read

Mohsen Fallahnejad

Nov 6

Hidden Classes in V8: Why Object Shape Changes Speed

#javascript #v8 #performance #hiddenclasses

5 min read

Mohsen Fallahnejad

Nov 6

V8 Garbage Collection: Why Middle-Aged Objects Are the Expensive Ones

#javascript #v8 #node #performance

5 min read

Mohsen Fallahnejad

Nov 6

Layout Thrashing: Why Reading offsetWidth in a Loop Freezes the Page

#javascript #browser #performance #layout

4 min read

Mohsen Fallahnejad

Nov 6

CPU Cache and JavaScript: Why Sorting an Array Can Make Loops 7x Slower

#javascript #v8 #performance #cpucache

4 min read

Mohsen Fallahnejad

Nov 3

What is Docker? The 2-minute mental model

#docker #basics

1

1 min read

Mohsen Fallahnejad

Nov 3

MVVM, Micro‑Frontends, and Domain‑Driven Frontend — A Practical Guide

#architecture #frontend #mvvm #microfrontends

4 min read

Mohsen Fallahnejad

Nov 3

Next.js App Router Caching — Cheat Sheet

#nextjs #caching #approuter #performance

2 min read

Mohsen Fallahnejad

Nov 3

Microtask vs Macrotask in JavaScript — With Node.js vs Browser Notes

#javascript #eventloop #microtask #macrotask

2 min read

Mohsen Fallahnejad

Nov 3

JavaScript Promises Explained

#javascript #async #promise #eventloop

2 min read

Mohsen Fallahnejad

Nov 3

JavaScript Closures — A Simple Deep Dive

#javascript #closures #scope #lexicalenvironment

3 min read

Mohsen Fallahnejad

Nov 3

Prefetching in Next.js Links Explained

#nextjs #link #prefetch #approuter

2 min read

Mohsen Fallahnejad

Nov 3

BroadcastChannel API in JavaScript

#javascript #webapi #broadcastchannel #multitab

2 min read

Mohsen Fallahnejad

Nov 3

React Context Explained: How It Works Under the Hood

#react #context #hooks #statemanagement

3 min read

Mohsen Fallahnejad

Nov 3

React Fiber Explained: How React’s Engine Actually Works

#react #fiber #reconciliation #concurrent

3 min read

Mohsen Fallahnejad

Nov 3

useDeferredValue Explained: Keeping React UIs Responsive

#react #hooks #concurrent #performance

1

1 min read

Mohsen Fallahnejad

Nov 3

Are TypeScript Enums a Good Idea? (Bundle Size & Runtime)

#typescript #enums #bundlesize #performance

2 min read

Mohsen Fallahnejad

Nov 3

Why async/await Doesn’t Make JavaScript Code Parallel

#javascript #async #await #promises

2 min read

Mohsen Fallahnejad

Nov 3

How Promise.all Works in a Single-Threaded JavaScript World

#javascript #promises #eventloop #async

2 min read

Mohsen Fallahnejad

Nov 3

Web Workers Explained for Frontend Developers

#javascript #webworkers #performance #parallelism

2 min read

Mohsen Fallahnejad

Nov 3

Promise.all vs race vs any vs allSettled: When Do You Stop Waiting?

#javascript #promises #async #eventloop

3 min read

Mohsen Fallahnejad

Nov 3

queueMicrotask Explained: The Smallest Async Queue in JavaScript

#javascript #eventloop #microtask #async

1 min read

Mohsen Fallahnejad

Nov 3

CDN Explained: What It Is, How It Works, and How to Use It in Next.js

#cdn #nextjs #performance #frontend

2 min read

Mohsen Fallahnejad

Nov 3

React memo vs useMemo vs useCallback — When to Use Which

#react #performance #hooks #memoization

2 min read

Mohsen Fallahnejad

Nov 3

CORS Explained Simply — Why Your Fetch Works in Postman but Fails in the Browser

#cors #http #security #fetch

5 min read

Mohsen Fallahnejad

Nov 3

?? vs || — The Default-Value Trap That Breaks Real Apps

#javascript #typescript #operators #interview

3 min read

Mohsen Fallahnejad

Nov 3

React useEffect Dependencies — The Bug That Keeps Coming Back

#react #hooks #useeffect #closures

4 min read

Mohsen Fallahnejad

Nov 3

Debounce vs Throttle — One Sentence to Remember Forever

#javascript #performance #debounce #throttle

3 min read

Mohsen Fallahnejad

Nov 3

The Leaderboard That Ranked 9 Points Above 100

#javascript #arrays #sort #gotchas

4 min read

Mohsen Fallahnejad

Nov 3

You Selected Rows 3, 8, 12, 15 and 20. JavaScript Checked 3, 1 and 8.

#javascript #arrays #parseint #gotchas

4 min read

Mohsen Fallahnejad

Nov 3

One Line in My Root Layout Turned 158 Static Pages Into 0

#nextjs #approuter #performance #caching

5 min read

Mohsen Fallahnejad

Nov 3

JavaScript ASI: Why return on Its Own Line Gives undefined

#javascript #asi #semicolons #syntax

4 min read

Mohsen Fallahnejad

Nov 3

The $4.35 Item That Was Charged $4.34

#javascript #numbers #floatingpoint #money

4 min read

Mohsen Fallahnejad

Nov 3

The Leaderboard Arrived Sorted. JavaScript Re-sorted It by User ID.

#javascript #objects #json #map

4 min read

Mohsen Fallahnejad

Nov 3

Scrolling My Blog Index Prefetched All 51 Posts. One Config Line Cut It to 90 kB.

#nextjs #link #prefetch #performance

4 min read

Mohsen Fallahnejad

Nov 3

The Server Action That Ran Twice, but Only on localhost

#nextjs #react #serveractions #strictmode

4 min read

Mohsen Fallahnejad

Nov 3

useTransition Explained: Make React Feel Instant

#react #hooks #concurrent #performance

3 min read

Mohsen Fallahnejad

Nov 3

JavaScript Generators & Iterators — Lazy Sequences Explained

#javascript #generators #iterators #es6

3 min read

Mohsen Fallahnejad

Oct 31

I Optimized a Button From O(n) to O(1). The Speed Didn't Matter.

#bigo #algorithms #performance #react

8 min read

Mohsen Fallahnejad

Oct 14 '25

Understanding HttpOnly Cookies: The Envelope JavaScript Can't Open

#cookies #security #web #nextjs

3

4 min read

Mohsen Fallahnejad

Sep 29 '25

Why MUI Avoids Theme Flash on First Load (Dark/Light Mode)

#mui #nextjs #darkmode #hydration

2 min read

Mohsen Fallahnejad

Sep 29 '25

Deep Copy vs Shallow Copy in JavaScript

#javascript #copy #objects #cloning

2 min read

Mohsen Fallahnejad

Sep 29 '25

Why setState Doesn’t Cause Hydration Errors

#react #hydration #setstate #nextjs

2 min read

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