why javascript manufacturers have desktop web and mobile ver

why javascript library manufacturers have desktop web and mobile web versions ?

There is some technical explanation about why the javascript libraries manufacturers have to create 2 types completely different? One for Web development for desktop and one for mobile web?

dHtmlx -> dHtmlx touch
Extjs -> sencha touch
jQuery -> jQuery mobile

is frustrating to think that developers have no solution but to develop two programs or two different interfaces for an application that is after all a website.

what would be the recommended practices to create a single application that runs on both desktop web and mobile web? Or just resign yourself to always create two applications?

I don't want to create an app-mobile, but i would like to see my webpage and interact with it in the same way in web desktop browser and in mobile browser.

UI of mobile devices and desktop’s (devices with big screen) is different.

You will want to have big buttons, and touch oriented controls for mobile devices, and mouse oriented controls with medium-to-small controls on desktops. Small screen space on mobile devices requires different information layout, so you will need to design two different layouts anyway.

On good side, we are working on migration both libs to some unified solution, where the same API can be used for any platform ( still different screens will require different design solutions )