A web-based tool to practice with a blank problem set and answer key, one problem at a time.
Uses pdf.js to render two PDFs on top of each other in an HTML5 canvas, and allows you to erase the canvas on top for only small sections of the page. I hacked this together really quickly, and might clean it up someday.
The source code is based on: Mozilla’s PDF JS example (quite heavily, I might add): https://github.com/mozilla/pdf.js/blob/master/examples/learning/helloworld.html And this CodePen: https://codepen.io/silvertae/pen/GRzdqpa