Complex sentence: Most HTML5 applications would be nothing without at least one and probably both of these and when people talk about programming HTML5 applications they are actually usually talking about developing stuff using all of these and possibly more (for example server side programming).
Split into simpler sentences: Most HTML5 applications would be nothing without at least one and probably both of these and maybe even more. And when people talk about programming HTML5 applications they are usually talking about developing stuff using all of these and possibly more (for example server side programming).