| Xiaoming Shi | 73dfa20 | 2020-03-12 11:31:35 -0700 | [diff] [blame] | 1 | <!DOCTYPE html> |
| 2 | <div id="target">target</div> |
| 3 | <script> |
| 4 | var delay = 100; |
| 5 | var results = []; |
| 6 | |
| 7 | function waitForNotification(f) { |
| 8 | setTimeout(() => { |
| 9 | requestAnimationFrame(function () { |
| 10 | requestAnimationFrame(function () { |
| 11 | setTimeout(f) |
| 12 | }) |
| 13 | }) |
| 14 | }, delay) |
| 15 | } |
| 16 | |
| 17 | window.addEventListener("message", event => { |
| 18 | waitForNotification(() => { |
| 19 | window.parent.postMessage(results.map(e => e.isVisible), "*"); |
| 20 | results = []; |
| 21 | }); |
| 22 | }); |
| 23 | |
| 24 | onload = () => { |
| 25 | var target = document.getElementById("target"); |
| 26 | var observer = new IntersectionObserver(entries => { |
| 27 | results = entries; |
| 28 | }, {trackVisibility: true, delay: delay}); |
| 29 | observer.observe(document.getElementById("target")); |
| 30 | window.parent.postMessage("", "*"); |
| 31 | }; |
| 32 | </script> |
