Reading this book, you may feel like you're getting mentoring from a long-time, grizzly web developer who's been deep into it from the very beginning. An example of a bit of wisdom from the book:
When you load an image in a web application, the original file size matters only in the data transfer. Once the file is on the browser, it is decoded in memory and it is always treated as a bitmap. Therefore, the size in memory can be calculated as width × height × bits per pixel. We should be careful, therefore, about loading big image files even if they are small in terms of bytes. Just to give an example, a full-screen image on a third-generation iPad will typically use around 12 MB of RAM.
Using more RAM will impact website performance when loading, scrolling, and returning from a frozen state (for example, when changing tabs).Obvious? Maybe, in retrospect. As a programmer, I've known that graphics chips and low-level rendering routines don't deal with PNG, but rather with bitmaps that occupy RAM. But I didn't apply this knowledge to mobile web until reading this. This book has more than its share of these.