This is an interactive calculator that can be used with button clicking as well as the keyboard. The ? button shows you the shortcuts for each button. Number buttons map directly with their keyboard values. This is screen reader friendly as well.
It was built with Vue.js, and has Jest unit tests and Nightwatch e2e tests. The Git repo can be found below, as well as the demo page. You can install this calculator app for personal use, using the commands in the GitHub README.md. It requires Node.js to run locally and to build.