window.stop()
seems to work (as the Stop button on the browser . However, this does not work in IE. worked on it for a while and eventually figured it out.
Use the code below for cross browsers solution. It works with FF3.5.2,3.6.3 Safari 3.1 and IE 7 and 8.
if(navigator.appName == 'Microsoft Internet Explorer') { window.document.execCommand('Stop'); } else { window.stop(); }
Good Luck