43 lines
841 B
HTML
43 lines
841 B
HTML
<!DOCTYPE html>
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<style>
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html, body {
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margin: 0;
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}
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#target {
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width: 100px;
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height: 100px;
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}
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</style>
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<div id="target">target</div>
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<script>
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var delay = 100;
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var results = [];
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function waitForNotification(f) {
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setTimeout(() => {
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requestAnimationFrame(function () {
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requestAnimationFrame(function () {
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setTimeout(f)
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})
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})
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}, delay)
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}
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window.addEventListener("message", event => {
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waitForNotification(() => {
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window.parent.postMessage(results.map(e => e.isVisible), "*");
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results = [];
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});
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});
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onload = () => {
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var target = document.getElementById("target");
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var observer = new IntersectionObserver(entries => {
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results = entries;
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}, {trackVisibility: true, delay: delay});
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observer.observe(document.getElementById("target"));
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window.parent.postMessage("", "*");
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};
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</script>
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