I am wondering if this is possible or not to run the javascript while loading a website which I don't have access to edit its code. For example, like running alert('Example') when I go into example.com. I have thought about using the inspect feature to edit the html code with onload function. But the problem is the html you edited on the page does reset everytime you reload it. So is there any way to run JS automatically when I have loaded a specific page, which I cannot change its default html layout