Numbers — even percentages — aren't always user-friendly. Assistive technologies present aria-valuenow as numeric values. If a progress bar is at 8%, what does that mean? aria-valuetext provides a way of presenting the current value in a more user-friendly, human-understandable way. For example, a battery meter value might be conveyed as aria-valuetext="8% (34 minutes) remaining".
The aria-valuetext attribute is used with the aria-valuenow attribute, not instead of it, unless that value is not known.
aria-valuetext is only needed when the numeric value of aria-valuenow is not meaningful. For example, a range's values are numeric but may be used for non-numeric values, such as college class level. The values of aria-valuenow for a 4-year college could range from 1 through 4, which indicate the position of each value in the value space. In this case, the aria-valuetext could be one of the strings: "first year", "sophom*ore", "junior", and "senior".
If the numeric value is meaningful, such as a spinner with aria-valuenow="3" for how many pizza slices you want to order, aria-valuetext is not needed.
When both the aria-valuetext and aria-valuenow are included, the aria-valuetext is announced. When there is no aria-valuetext attribute, assistive technologies will announce the aria-valuenow attribute for the current value.
