GitHub Split View Extension

A browser extension that enables a side-by-side (Split View) editor for Issues & Discussions & Pull Requests, Descriptions & Comments, and README files.

🛑 Problem

GitHub's default Markdown editor requires users to constantly switch between "Write/Edit" and "Preview" tabs to verify formatting. This context switching breaks the workflow and makes editing long documents frustrating.

✅ Solution

This extension injects a Split / Unsplit control directly into the interface, allowing simultaneous writing and previewing.

Zero Dependencies. The extension does not use any third-party text editors. It leverages the native GitHub textarea and preview renderer.

🎯 Supports:

• ✅ Issue description & comments
• ✅ Pull Request description & comments
• ✅ Discussions description & comments
• ✅ README files (and other markdown files)

💡 Why split on the Preview tab?

The architecture relies on GitHub's DOM behavior:

• When the Write tab is active, the Preview HTML is unmounted (removed from DOM).
• When the Preview tab is active, the Editor/textarea is mounted but hidden via CSS.
• By activating the Preview tab and forcibly displaying the hidden Editor via CSS Grid, we achieve a dual view without complex state management or double-rendering.

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Example