Why does the cursor or focus jump around on my website?

Jumping focus caused by source code order

A focus that jumps in all directions usually occurs because the order in which elements appear in the source code does not match the order in which they are displayed on screen. When navigating through a page using the Tab key, users expect the focus to move smoothly from top to bottom and left to right — logically following the reading direction. If a menu, pop-up, or sidebar is positioned elsewhere on screen via CSS than where the element appears in the code, the focus visibly jumps back and forth: first downward, then all the way back up, then to a button that was already visually passed.

A common cause is a `tabindex` value that has been manually set to a number higher than zero, which pulls elements out of their natural order. Cookie banners, filters that load dynamically, and modal windows that do not properly trap focus also cause this effect — the focus sometimes disappears entirely from view, hidden behind the banner or underneath an overlay still open. To reproduce this, the best approach is to navigate through the checkout yourself using only the keyboard. how to test whether an online shop is keyboard operable describes how that test works in practice. Often the focus order turns out to be related to the same elements that also cause problems with cookie banners and pop-ups, because those are overlaid on top of the page first.

Where this appears in WCAG 2.1: criterion 2.4.3

This requirement is found in WCAG 2.1 under success criterion 2.4.3, "Focus Order", which requires that the order in which elements receive focus preserves the meaning and usability of the page. This is a Level A criterion, and therefore also part of Level AA, which is what EN 301 549 amounts to in practice. Research by the ACM into the accessibility of online shops shows that this type of navigation problem occurs regularly in practice and is experienced as troublesome by users. An automated scan can detect whether a `tabindex` with a positive value is present, but whether the focus order actually feels logical to someone who cannot see the page is something that an automated accessibility test cannot fully determine — that remains dependent on manual review.