I wrote this tool for matrix calculations at https://www.matrizen-rechner.de while taking calculus 1 to verify my results and for a better understanding. This small project became bigger than expected. In the last few years it had more than 250,000 views.
--> Please note: I wrote this a very long time ago without having any javascript experience. I never intended for it to become this big and neither intended to publish the code back then. I promise, I never really used jacascript ever again. The html part is even worse. Python and C++ is where it's at but javascript was convenient for this project.