UA Ledger · Playable Test Bench · draft for review

Require both intersection and document visibility before advancing

Teaching laboratory. Cases run in this page against the authored functions. This is not a device panel, network approval, analytics-delivery proof or campaign result. Inputs are synthetic.

An element can remain geometrically inside a viewport while its document is hidden. This fixture checks a deliberately simple activity gate that requires both conditions.

Primary documentation: MDN: viewability gate (body read 2026-09-19).

Cases

What a pass does not prove

The threshold is a teaching choice, not an ad-network rule. A passing function demonstrates Boolean gating for supplied inputs, not a physical visibility observation. Occlusion, host lifecycle events and the measurement definition used by a network remain outside this test.