<!DOCTYPE HTML> <html> <!-- https://bugzilla.mozilla.org/show_bug.cgi?id=1151421 --> <head> <title>Test for Bug 1151421</title> <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/> </head> <body> <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1151421">Mozilla Bug 1151421</a> <script type="application/javascript"> /** Test for Bug 1151421 **/ SimpleTest.waitForExplicitFinish(); function childLoad() { // Spin the event loop so we leave the onload handler. SimpleTest.executeSoon(childLoad2); } function childLoad2() { let cw = iframe.contentWindow; let content = cw.document.getElementById("content"); // Create a function to calculate an invariant. let topPlusOffset = function() { return Math.round(content.getBoundingClientRect().top + cw.pageYOffset); } let initialTPO = topPlusOffset(); // Scroll the iframe to various positions, and check the TPO. // Scrolling down to the bottom will adjust the page offset by a fractional amount. let positions = [-100, 0.17, 0, 1.5, 10.41, 1e6, 12.1]; // Run some tests with scrollTo() and ensure we have the same invariant after scrolling. positions.forEach(function(pos) { cw.scrollTo(0, pos); is(topPlusOffset(), initialTPO, "Top plus offset should remain invariant across scrolling."); }); positions.reverse().forEach(function(pos) { cw.scrollTo(0, pos); is(topPlusOffset(), initialTPO, "(reverse) Top plus offset should remain invariant across scrolling."); }); SimpleTest.finish(); } </script> <!-- When the iframe loads, it calls childLoad(). --> <br> <iframe height='100px' id='iframe' src='file_bug1151421.html'></iframe> </body> </html>