This body text should render first, before the Javascript alert pops up, and never disappear from the browser window under any condition. It shouldn't disappear whether it's opened in a new tab or refreshed, and it shouldn't disappear whether or not "Disable cache" is toggled in devtools. As you can see in the source, index.html is the functional minimum, and the script tag occurs just before the body ends. Under no circumstances should the app.js alert script block this body from rendering.