nolanlawson/test-finalization-registry.html

## test-finalization-registry.html
<!doctype html>
<html>
<button id="derefKey">Deref key</button>
<button id="derefValue">Deref value</button>
<script type=module>
  const reg = new FinalizationRegistry(held => {
    console.log('gced', held)
  })

  const map = new WeakMap()

  window.reg = reg
  window.map = map

  class MyKey {
  }

  class MyValue {
  }

  window.key = new MyKey()
  window.value = new MyValue()
  let array = [new WeakRef(value)]
  map.set(key, array)

  reg.register(value, array)
  reg.register(key, "the key")

  derefKey.addEventListener('click', () => {
    window.key = undefined
  })
  derefValue.addEventListener('click', () => {
    window.value = undefined
  })
</script>
</html>
	<!doctype html>
	<html>
	<button id="derefKey">Deref key</button>
	<button id="derefValue">Deref value</button>
	<script type=module>
	const reg = new FinalizationRegistry(held => {
	console.log('gced', held)
	})

	const map = new WeakMap()

	window.reg = reg
	window.map = map

	class MyKey {
	}

	class MyValue {
	}

	window.key = new MyKey()
	window.value = new MyValue()
	let array = [new WeakRef(value)]
	map.set(key, array)

	reg.register(value, array)
	reg.register(key, "the key")

	derefKey.addEventListener('click', () => {
	window.key = undefined
	})
	derefValue.addEventListener('click', () => {
	window.value = undefined
	})
	</script>
	</html>