ES Modules

Security notes, SOC lab write-ups and tested code by Mahir Faysal, a SOC Level 1 cybersecurity learner in Bangladesh, plus notes from my Next.js and Gemini projects. Sample posts are marked and drafts stay in the admin area.

All notes Coding tips · 176 Learning notes · 25 Practice · 1

Coding tips

ReferenceError: x is not defined in JavaScript: 10 Causes and Fixes, from Typos and TDZ to require, __dirname and window in Node (Tested Examples)

JavaScript throws ReferenceError: x is not defined when it cannot find a variable with that name in any scope. Here are 10 tested causes in Node.js 24 and Chrome, from typos, block scope and the temporal dead zone to require, __dirname and window in ES modules and Node.

November 9, 2026 · 9 min read · 0 views