A question for UI/UX experts.

@atjn "Making it easy to revert the change" is often not an option. The whole point is to notify them of an action that is inherently irreversible.

@xahteiwi

In one instance I used a message-box with a text-input: 'This will do X and be irrevocable. If you're sure, that's what you really want TYPE "acknowledged" in the field below.'

It wasn't popular, but for the ~10 years it lingers in the app, I have never been called to restore data changed/deleted by that part of the program.

@xahteiwi Warn the user ahead of time that this is a two step process. Once they have completed step one, refer them to step two which should be listed in some form of inbox or notification system so that the detail is not lost.

It's possible, although awkward, to take a leaf out of FORMAT's book and ask someone to put in the name of whatever they're changing manually, or their password again.

Really though, it's most importantly about arse covering. No matter what action is taken some users will not worry about consequences until later.

Also, it usually involves code programmers don't want to write, but enforcing a save state or a cool off period helps.

You are about to delete all your data, are you sure? Y/N
Please insert disk to back up your data first or type in 'I am an idiot' to skip this
Please type in your password again to confirm you are a smartarse who will definitely not regret deleting all your data without a backup

@xahteiwi The Linux Terminal classic is "type out the letters "yes"" or similar.

@xahteiwi The correct(tm) way to do it is undo. Undo can take different shapes or forms. It can be immediate like in a word processor or indirect like with the recycle bin. Undo is backed up by usability research.

If you cannot offer undo, something like GitHub's "Enter the text ... below" is an option.

@xahteiwi make them think, make them do something unexpected, make them do something more involved than a simple click.

Entering a text like "yes, please delete stuff xyz" is a cheap a and simple method.

It also helps to visually separate those dangerous actions from others (the "danger zone" to be found on some platforms). While probably a small effect, it somewhat tunes the mindset.

@xahteiwi Modals were not good even before the advertising industry. They are bad for accessibility, they constrain the user's options, it's easy to design them badly ("How do I get out of this?") and can contribute to disorientation. Modals are only okay (not good) for very narrow use cases.

@xahteiwi Confirmation has largely fallen out of favour for that reason.

But:

1. Make it reversible if possible eg. keep backups in the background.
2. Friction - put it a couple of layers down. More affirmative action needed.
3. Big Red Scary Letters. Not just a benign popup.

@xahteiwi

It depends a lot on the use case but there are a bunch of old ideas that are relevant.

Apple's HIGs from 30+ years ago told you never to put 'yes' or 'no' or 'okay' on dialog box buttons. The buttons should always be verbs or verb phrases. For example, don't do:

'Erase your disk?' [ No ] [ Yes ]

Instead, do:

'Erase the disk?' [ Do not erase ] [ Erase the entire disk ]

This means that even people who don't read the question do read the answer before selecting it. For very high stakes things, you can require people to type 'I wish to erase the entire disk and I know that this cannot be undone' or similar, rather than a button.

For slightly lower-stakes thing, people sometimes disable the proceed button in the dialog for a few seconds. This solves two problems:

• User clicks before reading.
• Dialog appears and the user aims to click on something else that happened to be below the dialog.

There's also Raskin's First Law: A program must not harm a user's data or cause a user's data to come to harm.

This means that you need to make these operations support undo. For erasing an entire disk, that's not feasible, but for most things it is. Don't delete things, move them to a to-delete area. This is why MacOS had a rubbish bin from the start: delete moved things, if you didn't mean to delete them there was a move-back (undelete) button.

For a lot of things, starting with a non-destructive model makes sense. For example, if your file format includes unlimited undo history, you can add a 'publish' button that gives you a new copy without undo history. That means that you never have destructive operations. Similarly, if you're running some semi-arbitrary code, do it in a sandbox, unconditionally. Don't ask people 'do you want to trust this probably malicious thing?' just treat it as malicious and sandbox it.

@aha The correct way is eminently inapplicable if what the confirmation is meant to confirm is permanent deletion. (Which in some circumstances you might be required, by law or otherwise, to offer as an option.)

@xahteiwi

One idiom that's become common in games is that for important actions you can't just click a button -- you have to click and hold for a second or two while a visual gauge fills up on the screen.

You can combine this with a pop-up, so that clicking "Cancel" immediately closes the pop-up without doing anything, but to actually execute the delete action you need to press and hold the "Delete" button for five seconds.