How to connect js files in Gupl?

Question

Frontend

Hello! Not so long ago I have been studying and trying to set up Gulp for myself.
So far, it looks very simple to me. That is, I do not split into different files with tasks and so on.
It turned out to set up pug, scss, images, but I can’t figure out how to do it with js.
For example, I downloaded jquery manually from the site and put it in the src / js folder and I want it to get into build / js
How can I do this?