Can I Customize the BeforeUnload Popup Message?

Custom Messages in BeforeUnload Popups: A Browser Compatibility Saga

Question:

Can you display a custom message in the beforeunload popup, and how do you achieve it?

Answer:

Tl;dr: Custom messages are no longer supported in most modern browsers.

History and Compatibility:

In the past, custom messages could be displayed using methods like confirm, alert, or event.returnValue. However, these methods have been disabled for security reasons.

Current State:

Currently, most major browsers, including Chrome, Opera, Firefox, and Safari, do not allow custom messages in the beforeunload popup.

Workaround for Older Browsers:

If you still need to support older browsers, you can use the following methods:

• jQuery:

$(window).bind("beforeunload",function(event) {
    return "You have some unsaved changes";
});

• Javascript:

window.onbeforeunload = function() {
    return "Leaving this page will reset the wizard";
};

Important Note:

Confirm or alert cannot be used within the beforeunload event handler.

Caveats:

• Not all browsers support beforeunload messages.
• Firefox requires some user interaction before the message appears.
• Browsers may add additional text to the custom message.

Browser Support and Removal History:

• Chrome removed support for custom messages in version 51.
• Opera removed support for custom messages in version 38.
• Firefox removed support for custom messages in version 44.0.
• Safari removed support for custom messages in version 9.1.

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