<!-- Any copyright is dedicated to the Public Domain. http://creativecommons.org/publicdomain/zero/1.0/ --> <!doctype html> <html> <head> <meta charset="utf-8"/> <title>Performance test page</title> </head> <body> <script type="text/javascript"> "use strict"; let x = 1; function test() { document.body.style.borderTop = x + "px solid red"; x = 1 ^ x; // flush pending reflows document.body.innerHeight; } // Prevent this script from being garbage collected. window.setInterval(test, 1); </script> </body> </html>