Copying code block content doesn't preserve newlines on Firefox

[Martinsos]

🐛 Bug Report

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io
• I have read the console error message carefully (if applicable)

Description

Open https://docusaurus.io/docs/markdown-features/code-blocks in Firefox, select piece of code from code block, press Ctrl+C to copy it, paste it anywhere (e.g. in text editor), and notice how newlines are lost.

On Chrome this problem doesn't exist and newlines are correctly preserved/captured.

If "copy" button (in the top-right corner) is used, newlines are preserved though, even on Firefox. But "copy" button requires copying the whole block of code, you can't copy just part of it.

I tried doing the same thing at https://mdxjs.com/, and there copying works ok, newlines are preserved on Firefox.

Have you read the Contributing Guidelines on issues?

Yes

Your environment

ArchLinux 5.14.7-arch1-1, Firefox 93.0 (64-bit).

[slorber]

Couldn't reproduce on Firefox 0.92 MacOS

[matijaSos]

I have the same problem as @Martinsos on Firefox 93.0 MacOS Catalina 10.15.7

[Martinsos]

I was just able to reproduce the same problem on Windows 10, Firefox 93.0.

Here is GIF:

For some reason the pasting page didn't have "paste"but I used CTRL+V. Same behaviour is if I use right-click + paste in other editors.

[slorber]

oh I can reproduce indeed, it's the selection that can't copy lines, not the copy button that works everywhere.

[Martinsos]

oh I can reproduce indeed, it's the selection that can't copy lines, not the copy button that works everywhere.

Exactly! The problem is, sometimes a block of code might be relatively big and somebody might need to copy just a part of it. We had this situation in our tutorial, where we guide people to copy the highlighted piece of the code, and then user reported this issue on firefox.

[lex111]

Oh, this is quite serious bug, it should be fixed in this PR #5668.