Very Weird and Annoying Behavior of Messing up Pasted Text in Markdown Mode Editor

[firezym]

Description

When I copy Ctrl+C & paste Ctrl+V some long text with some markdown formats into the editor in markdown mode , there is a very great chance of messing up the text for display. The executed display and text content in the editor is inconsistant. Also Ctrl+Z to reverse editing has a high prob to break. You can see the actual difference if you switch between markdown and code mode. The behavior is very strange and annoying because I rely on the markdown to edit and when this happens, the original text can not be recovered completely.

Reproduce

Try to copy some long texts (especially markdown texts) into the editor in markdwon mode, as the gif shows. You can copy below texts as the gif:

```
aaaaaaaaaaaa
bbbbbbbbbbbb
cccccccccccc
dddddddddddd
eeeeeeeeeeee
```

Expected behavior

Texts are messed up and can not be recovered. The executed display and text content in the editor is inconsistant.

Context

• Operating System and version: Windows 10/11 for Chrome Frontend
• Browser and version: Chrome 120.0.6099.130 and also the latest official version of Chrome.
• JupyterLab version: 4.0.10 via official pip install, Tried Windows and Linux for Backend

jupyter_client            8.6.0
jupyter_core              5.7.1
jupyter-events            0.9.0
jupyter-lsp               2.2.1
jupyter_server            2.12.3
jupyter_server_terminals  0.5.1
jupyterlab                4.0.10
jupyterlab_pygments       0.3.0
jupyterlab_server         2.25.2

[firezym]

To add up, I also tried to copy these test texts from browser/vscode/notepad/word, it all cause the messed up texts. But If I try to copy it from the jupyterlab text editor in markdown/code mode to markdown cell, the texts will be fine.
```
aaaaaaaaaaaa
bbbbbbbbbbbb
cccccccccccc
dddddddddddd
eeeeeeeeeeee
```

[firezym]

@krassowski can you validate the above bug? Recently I am working a lot the markdown mode, it is really annying >..<
Could it be a bug involving CodeMirror?

[krassowski]

At a quick glance this looks like a duplicate of:

• Windows / Chrome: markdown code blocks get corrupted after pasting Windows line endings #14752

[firezym]

Yep, it looks related. I have that kind of error too, invisible results for markdown output. But I did not make that error gif.

[firezym]

I rely a lot on the markdown. But when the markdown is corrupted, I will need to create a new cell. But that will change the unique id of the cell, which I am using it for cross note book refencing. That's why I need the markdown cell to be stable for copy/paste editing...

[JasonWeill]

Closing as duplicate of #14752; let's keep the conversation going in the older issue. Thanks @firezym !