Update index.md

Author: adityaSrivastava29

index.md

@@ -1,10 +1,15 @@
-# JavaScript Interview Notes: Index
+# JavaScript Concepts with Code Examples and Interview Questions:
 
 Welcome! Use the links below to navigate the main topics:
 
+## 📚 Table of Contents
 - [Functions](functions/functions.md)
 - [Closures](Closures/closures.md)
 - [Event Loop](JS-Interview-Questions/eventloop.md)
+- [Higher Order Functions](JS-Interview-Questions/HigherOrderFunction.md)
+- [Map, Reduce, Filter](JS-Interview-Questions/map-reduce-filters.md)
+- [Polyfills](HigherOrderFunction/Polyfills.html)
+- [More Topics Coming Soon!]
 
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