Something that can come helpful:

1. Fetch: Cross-Origin Requests (Safe methods & headers; CORS)
   • access-control-expose-headers on the backend is set when the server sends a custom header in a response and allows frontend to read it
   • access-control-allow-headers allows frontend to set custom headers in a request that server will read
2. JavaScript execution context — lexical environment and block scope (var vs let vs function) Understanding Variables, Scope, and Hoisting in JavaScript
   • JavaScript Event Loop And Call Stack Explained Part 1
   • JavaScript's Memory Management: Heap and garbage collection explained Part 2
   • YouTube: Call stack, heap, queue, event loop - Talk.JS
   • Understanding the JavaScript runtime environment 
3. YouTube: JavaScript Event Bubbling and Capturing MADE SIMPLE!
   • YouTube: JavaScript's .sort method MADE EASY!
4. MYSTERY of "this" in JavaScript & Stale Closure
5. 3 Ways to use ? in JavaScript
   • !! convert value into Boolean
   • fnName.constructor.name
6. SameSite cookies explained
7. Same-Site vs Same-Origin
8. Cookies, CSRF, XSS
9. 9 Parts of URL
10. Great book about JS perfomance