Can I run a function of an extension from javascript?
I installed an extension to capture screens and wondered if it was possible to call the function Capture the entire screen from my own html file using javascript.
I have tried many libraries (html2canvas, webkit, etc.) and none were useful and that is why I wonder if I can use the power and simplicity of a chrome extension.
If it is not possible with Chrome, Firefox has that capability on their addons?
Yes, it's possible. Look at the Chrome extensions documentation