Using JS to control canvas implementation of the toy program that mimics the single, multiple, and drag controls on Windows

Features include: mouse click on the radio, drag multiple selection, CTRL + click the combo effect, the selected single or multiple canvas layers by mouse drag, arrow keys to move, delete deleted layer and so on.

The sense of complexity is mainly in the control logic, the following is all the code (with comments OH), you can directly copy Save as HTML file in the browser to see the effect

<! doctype> 

Using JS to control canvas implementation of the toy program that mimics the single, multiple, and drag controls on Windows