Update script.js

[Imran-imtiaz48]

Changes:

1. Used const and let instead of var for better scoping and avoiding potential issues with hoisting.
2. Removed redundant false argument in event listeners, as it’s the default.
3. Optimized the tocItems array creation using Array.from() instead of [].slice.call().
4. Used template literals for easier string interpolation in the path creation.
5. Simplified logic by using destructuring for targetBounds properties (top, bottom). This version should now be easier to maintain and perform slightly better.