demo · v130

Replay harness

Draw a real pointer path across two boxes; the page captures the trusted event stream (with its coalesced sub-events), constructs synthetic equivalents using new PointerEvent() with coalescedEvents targeting box-A and box-B, dispatches them, and runs a 6-test contract suite verifying the Chrome 130 behaviour.

1. record (real pointer)

box A
box B

2. replay (synthetic, untrusted)

box A
box B
draw a path across both boxes

recorded sub-events

(nothing yet)

received synthetic sub-events

(nothing yet)
contractstatus
T1 · synthetic parent dispatches—
T2 · coalescedEvents preserved as PointerEvents—
T3 · sub-event 1 target stays on box A (not retargeted to pad)—
T4 · sub-event 2 target stays on box B—
T5 · offsetX/Y on sub-events match author-supplied values—
T6 · sub-event isTrusted=false (still untrusted)—

the code

const subA = new PointerEvent("pointermove", {
  clientX: 30, clientY: 30, pointerType: "mouse"
});
Object.defineProperty(subA, "target", { value: boxA });

const subB = new PointerEvent("pointermove", {
  clientX: 200, clientY: 200, pointerType: "mouse"
});
Object.defineProperty(subB, "target", { value: boxB });

const parent = new PointerEvent("pointermove", {
  clientX: 100, clientY: 100, coalescedEvents: [subA, subB]
});
pad.dispatchEvent(parent);

// Chrome 130+: parent.getCoalescedEvents()[0].target === boxA  (preserved)
// Pre-Chrome 130:                              .target === pad   (retargeted)

see also