I need to notify the user under certain circumstances and have seen that confirm() and alert() shouldn't be used. Instead, a lot of questions mention using the modal thing in jQuery UI, especially if you need to style things. That's all fine and dandy, but, at the end of the day, what's the reason coders are saying you should stay away from it?
This is a pretty good example of how people feel, but pretty much any other question dealing with styling an alert box has the same comments. Is it only a styling issue or are there more fundamental reasons to shy away from this built-in functionality?
More importantly, none of the answers talk about what you ought to use instead. Are jQuery UI and similarly pre-built solutions simply the only answer? Why? Is it performance or security or inexperienced coders who need something easy to use or...?
Edit:
Okay, so let me clarify a bit. The reason I'm asking is because the alert functionality is to prevent a user from accidentally wiping out the work they've been doing since there are three ways to start a new plan on this page and each wipes out the existing inner html for the div where the plan is displayed.
Most of what I'm hearing is that it's bad for users and UI, but, if the anger-inducing, attention grabbing is what I want, what should I use instead? Someone mentioned that alerts / confirms halt JavaScript execution and may prevent you from using other tabs. That's closer to the functionality problems I'm expecting. I do understand that it's bad for UI, but I'm looking for more technical reasons here.