Number input

Carbon bakes keyboard operation into its components, improving the experience of blind users and others who operate via the keyboard. Carbon incorporates many other accessibility considerations, some of which are described below.

The Carbon number input replicates the behavior of the stock HTML component. The number input takes a single tab stop. The + and - buttons, operable by pointer, are not in the tab order. When the input has focus, the arrow keys give keyboard users the same ability to incrementally adjust the values. As well, users can directly type numeric values in the input. Only numerals are allowed to be entered.

Carbon provides errors and warning messages to assistive technology. This is an improvement on the stock HTML number input, which simply prevents the typing of alphabetic characters without explanation. Carbon also adds an error or warning icon and puts error messages in red as a further visual cue.

Design annotations are needed for the following instance.

Carbon offers the ability for the author to set minimum and maximum values for the input. When setting limits on number entry, designers should warn the user in advance, instead of users discovering limits through an error message. This is particularly the case if designers alter the step value, which determines the increment change when activating the +/- buttons or arrow keys. If a user directly enters a value that does not match the step increment, it will be disallowed for no apparent reason, so advanced warnings are crucial.

Keep this in mind if you’re modifying Carbon or creating a custom component.