alert(banana++) Should lock things up and not continue until OK is clicked. If it is just you and your application you can just spray paint from the hip the a

alert(banana++) Should lock things up and not continue until OK is clicked. If it is just you and your application you can just spray paint from the hip the alerts from top to bottom. After each line of html you can have one more <script>alert(banana++)</script>, in the middle of your css </style><script>alert(banana++)</script><style> etc If there are uhh thousands(?) of people actively using the page you put just one alert some place in the middle. Everyone will have to click on OK, the page crashes. You ask the crashee: Did it crash before or after the "make America great again" alert message. (call it something they would remember) Now you know the issue is in the top or bottom half. You move the alert to half way the half with the issue in it. If you can get some sort of reasonably consistent crashing you will find it pretty quick even in production. Hope this helps, or maybe it is a stupid idea and you could explain why.