Add Base64 Encode Decode in TypeScript

[ArihantJainWebDev]

I Am Adding a New Code Snippet in an Existing Language

• I fixed Add Base64 Encode Decode in Typescript #4573
• I did not include any extra folders/libraries
• I named the pull request using Add Base64 Encode Decode in TypeScript format

Other Notes

Implementation Details

• Implemented Base64 Encode/Decode functionality in TypeScript
• Uses Node.js Buffer API for encoding/decoding
• Includes comprehensive input validation:
  • Validates base64 string length (must be divisible by 4)
  • Checks for valid base64 characters only (A-Z, a-z, 0-9, +, /, =)
  • Ensures padding characters (=) only appear at the end
• Handles all error cases specified in .glotter.yml
• Follows existing TypeScript code style in the repository
• Updated README.md to reflect completion (24/38 programs)

Testing

Manually tested with multiple test cases from .glotter.yml:

• Encoding: lowercase strings, numbers, symbols, long strings
• Decoding: valid base64 strings
• Error handling: invalid mode, missing arguments, empty strings, malformed base64

All test cases pass successfully.

Contribution Context

This addresses the missing Base64 Encode Decode program listed in the TypeScript README.md under "Missing Programs" section.

[github-actions]

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[rzuckerm]

The code looks good, but please revert the changes to the README. This is automatically updated when the PR is merged.

[ArihantJainWebDev]

Sorry for my mistake!
I reverted the changes.

[rzuckerm]

I'm sorry, but you are going to have to resubmitted this without the README change. I can't seem to get the README change removed from this PR, and I'm worried about how this will affect the README automatiion.

[rzuckerm]

OK, I got it figured it. The README is properly reverted. Thanks for your contribution @ArihantJainWebDev !