Paint-like program in Javascript problem

Question

Hi, I'm developing a paint-like program in javascript and I have a problem.
When the user trigger the mousedown event on the canvas,and then move the mouse, it will be created rects on the mouse position. But if a move more quickly the mouse, there a strange interval in creating the rects. Maybe viewing the code and the final result you will understand
https://code.sololearn.com/WOR7EpHbYw7H/#html

Answer 1

Try to replace clientX and clientY with offsetX and offsetY

clientX is the offset from the client window.
offsetX is the offset from the parent element which is the canvas

Answer 2

I've tried, but it doesn't work yet