Promise vs setTimeout - Which Runs First? Event Loop Mechanics
Javascript Event Loop and Queues - Vanakkam Javascript - JS Tutorial | Tamil | 2025 | Part 3
This video is made in collaboration with JS Lovers Community.
Everything covered in this video is explained in detail in the following link : https://dev.to/jslovers/mastering-asy...
Chapters:
00:00 Intro
00:50 Single-Threaded Language
01:20 Call Stack
02:28 Web APIs
07:23 JS execution Flow
07:55 Example 1 (Basic)
11:50 Example 2
19:12 Example 3 (Advanced)
27:09 Task Starvation
28:38 Key Takeaways
29:50 Conclusion
Learn how the browser event loop, task queue, microtask queue, and Web APIs work together to enable non-blocking, asynchronous JavaScript.
JavaScript is a synchronous, single-threaded language, but async operations like setTimeout, fetch, and event listeners rely on the event loop, microtasks, and macrotasks for execution.
🔹 Key Concepts:
✅ JavaScript executes synchronous code first.
✅ Asynchronous tasks use Web APIs and the event loop.
✅ Microtasks (Promises, MutationObserver) execute before Macrotasks (setTimeout, event listeners).
✅ Fetch responses (microtasks) execute before setTimeout callbacks (macrotasks).
✅ Task starvation can occur if microtasks keep running without allowing macrotasks.
By mastering these, you can write efficient & bug-free async JavaScript! 🚀
Whatsapp Channel: https://whatsapp.com/channel/0029VaYI...
Join Membership: / @hareeshrajendran
📢📢📢📢 Social Media Links 📢📢📢📢
Mentorship 1:1 : https://www.meetmymentor.me/hareesh_r...
Buy me a coffee ☕️ : https://www.buymeacoffee.com/hareeshr...
LinkedIn: / hareesh-r
Instagram: / hareesh_._r
Facebook: / hareeshprogrammer
Twitter: / hareesh_dev
GitHub: https://github.com/hareesh-r
Curious to know more about me?: https://hareesh.web.app🚀
Your support means the world to me! 🙌 Let's build an awesome community together. 🌍✨
On this page of the site you can watch the video online Promise vs setTimeout - Which Runs First? Event Loop Mechanics with a duration of hours minute second in good quality, which was uploaded by the user Hareesh Rajendran 27 February 2025, share the link with friends and acquaintances, this video has already been watched 14,515 times on youtube and it was liked by 421 viewers. Enjoy your viewing!
