aria-valuenow property is used while developing range widgets. For a range widget a minimum and maximum values need to be defined. Examples of a range widget are sliders such as volume button on windows operating system. The volume button has a minimum value of 0% to a maximum value of 100%. Other range widgets include progress bars, scrollbars, spin buttons and sliders.
Aria-valuenow defines the current value in the range widget. aria-valuemax exposes the maximum value that is allowed in the range widget while aria-valuemin exposes the minimum value. If the author does not know the current value aria-valuenow should not be defined. The value of aria-valuenow should be any number between the values of aria-valuemax and aria-valuemin. Eg: If the value of aria-valuemin is 1 and aria-valuemax is 5 then the value of aria-valuenow should range between 1 and 5, it cannot be greater than 5 or less than 1. If the current value is a string instead of aria-valuenow use aria-valuetext property.
For progressbar and scrollbar widgets assistive technologies should inform the current value i.e. aria-valuenow in percent. If the aria-valuemin and aria-valuemax are not known use the current value as aria-valuenow and add percent indicator to it. If the aria-valuemin and aria-valuemax are known calculate the current position within the range in percent and define it as a value to be exposed with aria-valuenow property. For slider and spin button widgets use the current value to expose via aria-valuenow property.
Values of aria-valuenow property
The value of the aria-valuenow property must be a number. For progressbar and scrollbar widgets the value of aria-valuenow property must be in percentages. The value of aria-valuenow must be less than or equal to aria-valuemax property and greater than or equal to aria-valuemin property.
aria-valuenow used in roles
Inheritted into roles:
