In the 2000s JavaScript was inconsistent and limited in what it could do. When jQuery arrived it was a great tool to overcome that (I had actually started work

In the 2000s JavaScript was inconsistent and limited in what it could do. When jQuery arrived it was a great tool to overcome that (I had actually started work on something like it when I found out about it). In comparison today js is far better and much more consistent. Only use packages you need, not just because they are there. "View Source" will not get you far. If you mean use browser developer tools to view the js files, it will still be very very hard. Most of what you see will defy comprehension without knowing the background and design behind what is happening.