What does "jupyter labextension build ." command internally executing?

Hello team, I was working with open source jupyter labextensions(eg: spellchecker) and if we run yarn build in the project folder. It is internally calling jupyter labextension build . command. I know that this command is creating a subfolder with the name labextension folder inside the python package sub_folder(eg: jupyterlab_spellchecker) which consists of static compiled JS files but don’t know exactly which lines of code are getting executing internally when we run jupyter labextension build . command. I know it is bundling the typescript/javascript files via webpack but not sure about the lines of code which are getting executing. Can you please help me with this? The main reason of asking this, I want to perform the same thing that is creating static files under the labextension folder, by customising some of the things in it.

Best,
Raghav Mittal

Hi, could anyone please respond?

I know it is bundling the typescript/javascript files via webpack but not sure about the lines of code which are getting executing. Can you please help me with this? The main reason of asking this, I want to perform the same thing that is creating static files under the labextension folder, by customising some of the things in it.

If you are asking about jupyterlab side of things, exploring the source of the builder package may be a good starting point: jupyterlab/builder/src/build-labextension.ts at f7e5022946d0b8437f076484ef717e9e66cadc8c · jupyterlab/jupyterlab · GitHub

But if you are more generally interested in what webpack is doing under the hood, it is probably not the best place to ask.

As for things that you can customize, these are documented here: Develop Extensions — JupyterLab 4.1.6 documentation

if you don’t see the thing you want to change, I would suggest to be specific and open a very specific issue, with motivation and proposed solution, in the JupyterLab repository :slight_smile:

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Okay thanks for your reply. Let me be more specific, due to some current infra limitation, we don’t have the virtual environment and jupyterlab installed in it, that’s why we are not able to run the command jupyter labextension build . command on our remote machine. As the above command is internally executing the webpack config only, is it possible to run the webpack config independently of installing virtual environment and jupyterlab. If possible and feasible can you share that kind of webpack config?

Best,
Raghav Mittal

I am not sure if this is the right platform to ask this question, so created a new discussion in the jupyterlab git repo to ask the same: Can we run jupyter labextension build . command independent of virtual environment and jupyterlab installed in it? · jupyterlab/jupyterlab · Discussion #16191 · GitHub