Here I record some thoughts and background behind this book, so that I (or the future maintainers) can revise the book based on this thoughts. Since I don't think will remember all my ideas at the moments.
Readers on the web don't like to read a long article. Roughly, I try to limit one page not longer than 6-times Page Down key pressing (might have exceptional cases). If a page is too long, then I will split it by topics.
A sub-title helps readers to know the main topic for the subsequent paragraph. If they quickly scroll down the whole page, they can also get an overall idea of the page. Besides, sub-titles also help readers locate a topic they are interested easily and avoid them reading lines by lines.
I assume readers choose to learn one approach (either MVC or MVVM) at one time, so they don't read both approaches. When writing MVVM chapters, I don't assume readers have read MVC chapters. Therefore, I have to write duplicate content in both chapters.
since the complete source code is available, short code snippet is easy to read, to show the key point, and can eliminate explaining it with line numbers. Line numbers could change in the future.
It's unnecessary to include chapter number in an image file name since we might insert them in different chapters or chapter order could change in the future.
Created by https://www.draw.io, store in https://drive.google.com/open?id=1z2RUdSS5fNav2sS_bj_z3JeDkze2_UgI Some old images are created by MS Word.