Update index.js

[Imran-imtiaz48]

Key Refinements:

1. Consistent Formatting: Used consistent indentation, spacing, and formatting across the code for better readability.
2. Improved Comments: Added comments to clarify what each section does.
3. Refactored Logic: Simplified some loops and conditions for better readability.
4. Error Handling: Ensured that any errors are caught and handled, especially in fullscreen requests and exits.
5. Code Clarity: Used forEach for cleaner iteration and used optional chaining (?.) to avoid potential runtime errors. This code should now be easier to maintain, read, and debug while retaining its functionality across various browsers with different fullscreen APIs.

[sindresorhus]

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