If you don't have strong native JavaScript skills. Improve it first. And then, let's say you picked Vue.js. Googling MVVM and learn about the basic concept fro

If you don't have strong native JavaScript skills. Improve it first. And then, let's say you picked Vue.js. Googling MVVM and learn about the basic concept from your best backend language. (Reading as much as you can. Some good articles are written in other programming languages also.) And then, starting to read source code as much as you can. I won't pick big projects. Just pick any sources you think you're interested and understand it. After all, you will get the whole picture how the app should look like and why framework trying to do X & Y.