I mentioned earlier that one of the things the iPhone doesn’t support is the ability to display fixed position content at the bottom of the viewport, because you can scroll the entire viewport. This is incredibly annoying if you want to create a bottom tab bar, similar to the native app convention.

Richard Herrera created a JavaScript file that adapts for this (FIG 12-17) and is available for free for your iPhone web apps.

Unfortunately, because this script is technically a hack, it can be sluggish to scroll elements, especially if you have many tabs open in Safari. Following Richard’s work, Matteo Spinelli created another version of a fixed footer scroller that is a bit smaller in file size and performs a bit better.