Using HTML 5 to change the keyboard language on mobile devices

I think this's not really possible ,the problem you will encounter is that the keyboard is itself an application depends on the users locale , therefore you cannot change it directly from your web html page, nor can you guarantee that your user will have the "Arabic" charset and the keyboard depends alos on mobile device OS

Here's an example for html mobile input type :

http://mobileinputtypes.com/

Lang attribute was proprietary feature added by Microsoft to its Internet Explorer browser. It referred to scripting language not. It was used to identify what language to use to interpret scripts.

Read more: https://html.com/attributes/input-language/#ixzz6F9qYpJJ9

If you want to open keyboard in a particular language you cant do directly in web application.

But you could create your custom modals which will work as keyboards for different languages(look and feel should be of real keyboard but is not a generic device keyboard ). In this scenario when user clicks on input field you could trigger your custom modal to open. Generally in above scenario device keyboard will also be triggered. This can be stopped using inputmode='none' <input type="text" inputmode="none" /> Refer: https://css-tricks.com/everything-you-ever-wanted-to-know-about-inputmode/

In extend to e2rabi and Srikara B S, it's indeed not possible but there might be a workaround.

In one of the applications that's being build by my employer, they wanted a strict character set to be used. They basically set all inputs to contain the disabled property, and on click(touch) render a custom keyboard. Because of the disabled attribute the keyboard won't trigger, and using (basic) Javascript you can fill the input with the keys used on your custom keyboard.

This isn't the most viable method, but since you can't force a users keyboard language (especially since an OS like Android allows custom keyboards), it might be your only option if you want to force a specific keyset or scheme/layout.