Fabric.js How to fill an area outside of a shape with a different color and transparency?

Question

JavaScript

I am using fabric.js. I have a square, it has its own transparency, I need a fill around it, but with a different transparency. That is, it is impossible to impose a square on top. Please tell me how to do it?)

Answer 1

Overlay from below :P
Use a background with the desired transparency.
Attach a picture of what you are doing, well, the code will not hurt.