Mobile browsers lack many capabilities of mobile applications. This is due to the fact that browsers cannot replicate the same native platform widgets as HTML elements. We can try to do this, but it's often better to just use the native widget, rather than try to replicate it. Partly because this requires less maintenance effort on our part, and partly because using widgets that are native to the platform means that they're consistent with the rest of the platform. For example, if a datepicker in your application looks different from all the datepickers the user interacts with on their phone, this isn't a good thing. Familiarity is key and using native platform widgets makes familiarity possible.
User interactions on mobile devices are fundamentally different from the interactions that we typically design for on the Web. Web applications assume the presence of a mouse, for example, and that the click event on a button is just one phase. But, things become more...