Syntax highlights were gone in code cells for newly created notebooks

[MRYingLEE]

In the Vallina demo notebook and all newly created notebooks, syntax highlights were gone in code cells.

An example is as follows:

The previously created notebooks can show syntax highlights normally.

The same issue happened in both latest version of MS Edge and Google Chrome on Windows 11.

Please check. Thanks,

[MRYingLEE]

I found the direct reason.

In the previously created notebooks, the metadata for the notebooks are as follows: { "kernelspec": { "name": "xjavascript", "display_name": "JavaScript (xjavascript)", "language": "javascript" }, "language_info": { "codemirror_mode": "", "file_extension": "js", "mimetype": "text/x-javascript", "name": "javascript", "nbconvert_exporter": "", "pygments_lexer": "", "version": "ES6" } }

In the newly created notebooks, those are as follows: { "kernelspec": { "name": "xjavascript", "display_name": "JavaScript (xjavascript)", "language": "javascript" }, "language_info": { "name": "" } }

If I update the metadata of the newly created notebooks to the previous value, then the syntax highlights backs.

So far, I have no idea on the root reason.

[MRYingLEE]

The same issue happens in Xeus-Python also. So this must be a bug of Xeus.

[DerThorsten]

might also be an issue with jupyterlite itself.

On the xeus/c++ side, kernelspec / kernel info sits here https://github.com/jupyter-xeus/xeus-javascript/blob/main/share/jupyter/kernels/xjavascript/kernel.json.in and here https://github.com/jupyter-xeus/xeus-javascript/blob/main/src/xinterpreter.cpp#L129

I don't remember 100% where on the javascript side this info is consumed, but probably somewhere in https://github.com/jupyterlite/xeus/

[MRYingLEE]

The issue disappeared in the latest version.

I tested in both Edge and Chrom and also in both normal and inPrivate(incognito) mode.

Thanks,