<!DOCTYPE html> <html> <head> <script> var w; function b1() { w = window.open("404.gif", "w2", "f"); setTimeout(b2, 1200); } function b2() { w.close(); setTimeout(b3, 500); } function b3() { w.location = "data:text/html,2"; document.body.appendChild(document.createTextNode("Done")); } </script> </head> <body> <div><button onclick="b1();">Start test</button></div> </body> </html>