Warning Positive tabindex value

Example

<!-- Flagged: forces this field to be tabbed to first -->
<input tabindex="1">

<!-- Right: 0 makes an element focusable in natural source order -->
<div tabindex="0" role="button">Custom control</div>

<!-- Right: rely on the default tab order for native controls -->
<input>

Why it matters

By default, the Tab key moves focus through a page in source order, which usually matches the visual reading order. A positive tabindex pulls an element out of that order and gives it explicit priority — 1 before 2, 2 before 3, and so on — ahead of every element with no tabindex at all. On any page with more than one positive value, keeping the numbering consistent as the page evolves becomes fragile, and a single stray value creates a jarring jump in the tab sequence that has nothing to do with the visual layout. tabindex="0" is different and unaffected by this warning — it makes an otherwise non-focusable element (like a <div> acting as a button) focusable in its natural document-order position, which is the standard way to build accessible custom controls.