<!DOCTYPE html> <title>IntersectionObserver ratio with fractional bounds</title> <link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1278897"> <meta name="viewport" content="width=device-width,initial-scale=1"> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <style> #container { overflow: hidden; width: 500px; } #target { display: list-item; padding: 16.1px; background: rebeccapurple; } </style> <div id="container"> <div id="list"> <span id="target"></span> </div> </div> <script> async_test(function(t) { let target = document.getElementById("target"); let list = document.getElementById("list"); let observer = new IntersectionObserver(t.step_func_done(function(entries) { assert_equals(entries.length, 1); assert_equals(entries[0].intersectionRatio, 1); assert_equals(entries[0].isIntersecting, true); }), { root: list, threshold: 1 }); observer.observe(target); }); </script>