The alert method is a property of the window object so there is no real difference between window.alert, this.alert, and just plain alert by itself. So that is just about it when it comes to using alert, just pass in what you want to log and it should alert out to you.
This might work out okay if a developer is just working something out, but is not going to leave it that way, but when it comes to using alert in an actual production app of some kind that can get very annoying. There are other ways to log what is going on where even if it is left in place, will not greatly effect the behavior of the application.
So lets take a quick look at a simple innerText example for displaying something.
I just need to get a reference to an element by one means or another such as with document.getElementById. Once I have a reference to an element I can then use that as a way to display a message. A method like this can then be used to display a message in a browser window without having an annoying dialog box pop up each time.
The prompt method might still come in handy now and then, but for the most part I would prefer to go with input elements, or some other means of gathering user input that will not delay the event loop.
Once I have my custom log method defined I can then use it anywhere in my project where doing so is needed.