Where to find a book (or any learning resources) about designing web ui elements?

What are the possible ways to learn "designing web ui elements". I mean: 1. What I need to know to be able to create custom and reusable web ui element / component from scratch, or even how to learn to do "scratches'? How to decompose the topic into subtopics? 2. What are best resources for learning: courses (online/offline), books, conferences or work on real projects?

Example: My goal is able to create custom component for filtering data, different date/time pickers, popup and autocomple windows.

Thank you!