[inputmode] content attribute
The inputmode content attribute is an enumerated attribute that specifies what kind of input mechanism would be most helpful for users entering content into the form control.
It is extremely useful to be able to ask for the correct keyboard without having to change the type of your input element. There are so many examples where input[type=number] is really not applicable but you do want a numeric keyboard.
This is helpful for other reasons too. Currently type="number" is great and shows the correct keyboard on mobile devices. However any attempt to set a partial value, or use any of the selection properties/methods fails. Having the inputmode attribute available would mean we can choose the best input device keyboard but not suffer the side-effects of setting the field as number.
Daniel Aleksandersen commented
This is actually a really useful feature as input[type=number] has serious localization and usability issues.