Are You Sure? The UX of Confirmations

Imagine for a minute your web app has a “Delete” action. In HTML it takes this form:

<a class="delete" href="#">Delete Item</a>

The anchor is styled up with sexy CSS3 and functionality is implemented with an asynchronous JavaScript API call. Because we all care about accessibility (and standards) we provide a “no-JS” fallback:

<a class="delete" href="/item/delete/1/">Delete Item</a>

Lovely! It’s great to build on top of what works. “Web apps” are still websites, after all.

Now, I know what you’re thinking, “Delete” is a big commitment! What if the user triggers the link accidentally? What if the user has been conditioned through years of UI exposure to expect a modal window explaining the ramifications, or at least asking for confirmation? We could write a little script (jQuery, naturally) to hijack any element with the class “delete” and throw up a confirmation box. Similar to this:

$('a.delete').on('click', function(e) {
    return confirm('Are you sure?');

Replace confirm() with your fancy dialog of choice. The function [window.confirm]( provides a native dialog implemented by the browser. More on that later!

Browser confirm dialog in Mac OSX

That’s quite nice but searching the whole DOM for links is fairly intensive. There will also be the initial delay of execution while we wait for the DOMContentLoaded event. Users will quick trigger fingers will be able to click “Delete” and see no confirmation request. We also have the issue of microcopy hardcoded in our script (not the best place for it). We could mess around with additional data-* attributes but I have a better idea…

<a class="delete" href="/message/delete/1/"
   onclick="return confirm('Are you sure?')">Delete Item</a>

Boom! No dependancies, no need to worry about fast fingers, and browser support dates back to Netscape. (Event handler attributes like onclick are still a big part of HTML5, in case you were wondering.)

This is perfect for our needs but as you’ve probably noticed the native confirm dialogs are ugly as hell. On mobile devices (see Android 4.0 and iOS below) the dialogs look slightly better in my opinion. More importantly though, they work! Have you ever tried building a custom modal dialog for mobile browsers? Good luck with that!

Browser confirm dialog on Android 4.0 and iOS

Going native on mobile is undoubtedly the best experience. Even native mobile apps use native dialogs. Don’t even think about trying to implemented fixed positioning in a mobile web browser it will have you in tears (trust me). The question is: how do we go native on mobile, but provide a custom dialog design for desktop browsers like Chrome, while still gaining the benefits of inline event handlers? Check out the one I designed (based on TJ Holowaychuk’s UIKit):

Custom confirmation dialog

To provide both native and custom dialogs through confirm() we need to override the function.

Our problem is that the native dialog hangs the browser action in a way that we cannot. Any override we create for window.confirm must return false and then act asynchronously on later events. How can we do this when only a string is passed to the function?

The onclick attribute basically creates an event handler like this:

function(event) {
    return confirm('Are you sure?');

Note the event parameter. We need to access this object (a MouseEvent) to obtain the original target element and go from there. We could pass it through like this:

<a onclick="return confirm('Are you sure?', event)">

The native version of confirm will ignore the second argument (JavaScript isn’t fussy). But that’s not very clean, and there is a better way! When we redefine confirm we can actually access this event object.

window.nativeConfirm = window.confirm;
window.confirm = function(message) {
    var event = window.event || window.confirm.caller.arguments[0];
    // ...

First we check the window object, old Internet Explorer will find an event chillin’ there. Other browsers can access the function’s caller. If no event exists we just return window.nativeConfirm(message); and be done with it. If the event does exist — and we’ve established that the user experience will be improved with non-native dialogs — we get the target element, read the href attribute, pop open a custom dialog with a callback that redirects on success, and return false to cancel the default onclick action.

My final implementation with extended functionality looks a little something like this:

<a onclick="return confirm('Are you sure?')" href="/action/">Delete Item</a>
window.nativeConfirm = window.confirm;
window.confirm = function(message, event, callback)
    // grab the event and target element (if they exist)
    var e = event || window.event || window.confirm.caller.arguments[0];
    var el = || e.srcElement;

    // go native if preferred, or no event/element
    if (useNativeConfirm() || !e || !el) {
        return window.nativeConfirm(message);

    // open custom dialog with callback function
    fancyConfirm(message, function(result) {
        if (result && el && el['href']) {
            window.location.href = el['href'];
        if (typeof callback === 'function') {

    // cancel onclick action
    return false;

By including useNativeConfirm() we can do some feature detection and browser investigation to determine what type of dialog to display. For mobile browsers this is essential. I’m still thinking about the best way to make this decision but a Modernizr media query test for small screens is a good start.

To recap the benefits of this technique:

  • Allows for native confirmation dialogs that are immediately present and supported by all browsers with no dependancies.
  • Is easily implemented within the HTML.
  • Has the ability to provide more attractive dialogs for browsers that can handle them while retaining native dialog use elsewhere (i.e. small screen/mobile).

I’ll whip up an example soon. Any thoughts?

Even if you don’t like the idea of redefining window.confirm or using event handler attributes, I’d still recommend avoiding custom dialogs on mobile devices.

More from me…

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