You can do it bro. Dockerfiles are basically just shell scripts with a few extras.
It uses npm to build so start with a node base container. You can find them on docker hub. Alpine-based images are a good starting point.
FROM appdynamics/nodejs-agent:23.5.0-19-alpine
RUN git clone https://github.com/stophecom/sharrr-svelte.git && \
cd sharrr-svelt/ && \
npm run build
If you need to access files from outside of the container, include a VOLUME line. If it needs to be accessible from a specific network port, add an EXPOSE line. Add a CMD line at the end to start whatever command needs to be run to start the process.
Read up on it a bit, it's fairly easy. It's similar to writing compose files but those are for using the image, dockerfiles are how you put it together. You get to decide very similar things to compose — what image to use, what ports to expose — but you also get to run commands to set up the insides of the image.
You do have to know a bit of Linux and how to setup the software you want to use though.