This version is old school.
Please find jQuery plugins on npm.
jqScribble - A touch enabled canvas drawing tool
by Jim Saunders
A small canvas drawing plugin. It lets you draw on a canvas, add an image to a canvas, and save your drawing as an image. A simple PHP file is included in the repo to demonstrate how you might save the image server side. It is touch enabled so you can draw using a finger on touch enabled devices as well as the mouse on standard devices.