The directory src/ contains the source code for the spectral-sequences module. This is compiled into bundle.js, which is what you should include into your webpage.
To install dependencies for compilation, run
$ npm install
This only has to be done once. Afterwards, to compile the source code into bundle.js, run
$ npm run build
Due to CORS restrictions, opening an file directly in a browser is unlikely to succeed. Instead, you should run a web server that serves the directory and then access localhost. To do so, navigate into the directory containing the source code, and run one of the following two commans:
$ python3 -m http.server 8080
$ npx http-server
Afterwards, direct your browser to http://localhost:8080/