ARIA property
aria-colindex
Which column a cell is in, counting from the real table rather than what is shown.
It fixes a cell's position in the full table rather than in the fragment you rendered. Change which columns are on screen and the indexes stay put, because they describe the data and not the view.
Which roles may carry aria-colindex
- Value
- integer
- Filed as
- A property, which is how ARIA files it and not a rule about how often it changes.
- Roles that inherit it
columnheader,gridcell,rowheader
Those lists are not advice. Browsers are required to ignore a non-global attribute sitting on a role that does not support it, so aria-colindex on the wrong element is not weak, it is absent. You can read it in the DOM and nobody using a screen reader can.
Every role above comes from the specification's own list for this attribute, checked name for name. The normative definition stays with the W3C, in the aria-colindex section of the ARIA specification.
Keeping aria-colindex true
This goes wrong when a column is inserted or reordered and the indexes are left where they were. They are still numbers, so nothing looks broken, and they now point at the wrong columns. That is the failure mode with no visible symptom. Compute the index from the data on every render rather than writing it in once. And keep it paired with aria-colcount, because a position with no total behind it leaves the listener holding half a fact.
How aria-colindex gets checked
There are test rules that check an ARIA attribute is one that exists, is allowed on the role underneath it, and carries a value of the right type. What they map to is ARIA's own author requirements rather than any WCAG criterion, so a misplaced attribute breaks ARIA without being a WCAG failure by itself. It becomes one under 4.1.2 Name, Role, Value the moment the missing or wrong value means the control's state cannot be worked out programmatically, which is what usually happens next.
Nothing automated catches the failure this page is about. A stale value is a valid value, on a permitted role, with the right type. It is only wrong about the world.
Attributes you will meet alongside aria-colindex
- aria-colspan How many columns a cell spans, when the markup cannot say so itself.
- aria-expanded Whether the thing this control opens is currently open.
- aria-level The depth of a heading or a tree item, counting from one.
- aria-posinset Which position this item holds in its set, when the markup does not contain the whole set.
- aria-rowindex Which row this is, counting from the real table.
- aria-rowspan How many rows a cell spans, when the markup cannot say so.
- aria-selected Whether an option, tab or row is the chosen one.
- aria-setsize How many items the set really holds, when only some are in the markup. Together with aria-posinset this is what makes an infinite list announce as 5 of 200.
Every ARIA state and property · Every ARIA role · ARIA explained