demo · v138

Tap vs hover

Desktop moderate eagerness fires on mousedown — ~80–200 ms before the click. Mobile has no mousedown equivalent. 138’s improvement: arm the prefetch on pointerdown/touchstart, giving the same 80–200 ms head start instead of waiting for the synthesised click.

desktop — hover & mousedown

armed: 0warmed: 0

mobile — pointerdown/touchstart (138)

armed: 0warmed: 0

the change

// In 138, the <script type="speculationrules"> with eagerness: "moderate"
// uses these heuristics:
//   desktop: link hover > 200ms OR mousedown
//   mobile:  pointerdown OR touchstart  <-- NEW in 138
//
// Result: moderate-eagerness prefetches arm 80–200ms before the click
// fires, on touch devices — matching desktop behaviour.

Before 138, mobile moderate-eagerness essentially never armed in time: the events the browser was watching for didn’t exist on touch. Sites had to drop to eagerness: "eager" or wire JS handlers to call document.prerendering-aware prefetches manually. 138 unblocks moderate eagerness for mobile traffic.

see also