<bmx-progress>
How far through something is.
The fainter fill behind the first is a
buffer — how much of a video has loaded against how much
has played, or how much of an upload has been accepted against how much has been sent. It is drawn and never
announced: a screen-reader user read two numbers for one operation learns less, not more.
value, which is a state rather than a missing input: work is happening
and nobody is pretending to know how much is left. aria-valuenow is omitted entirely, which is how ARIA
spells indeterminate — not aria-valuenow="0", which claims a position and is read as "nothing has
happened yet".
role="progressbar" announces nothing by itself
— changing aria-valuenow is silent in every major screen reader — so this component keeps a
live region beside it and speaks at milestones: every twenty per cent, and the finish. A hundred integers read aloud
over the top of whatever you were doing is the other half of the same defect, and the reason it is not every value.
Every property, event and method: https://docs.binarymission.co.uk/webcomponents/bmx/bmx-progress.html