Can I Still Customize Beforeunload Pop-up Messages?

Custom Messages in Beforeunload Popups

Background

The window.onbeforeunload event allows web developers to display a confirmation message when users attempt to navigate away from a page. Historically, setting a custom message in this popup was possible using methods like confirm, alert, or event.returnValue.

Current Status

Unfortunately, due to browser security enhancements, displaying custom messages in beforeunload popups is no longer possible in most modern browsers, including Chrome, Opera, Firefox, and Safari.

Alternative Approach

The return value of the window.onbeforeunload event handler can still be used to display a generic confirmation message. In jQuery, this can be achieved as follows:

$(window).bind("beforeunload", function(event) {
    return "Are you sure you want to leave?";
});

In plain JavaScript:

window.onbeforeunload = function() {
    return "Confirm your exit?";
};

Browser Compatibility

While not all browsers support custom messages in beforeunload popups, the return value approach is widely compatible. Note that:

• Firefox requires the user to have interacted with the page before the message will appear.
• Each browser may append additional text to the generic message.

Removed Support

The following browsers have removed support for custom messages in beforeunload popups:

• Chrome: Version 51
• Opera: Version 38
• Firefox: Version 44.0 (unconfirmed)
• Safari: Version 9.1

Conclusion

Custom messages in beforeunload popups are no longer supported by most modern browsers. Web developers can still display a generic confirmation message using the window.onbeforeunload event handler.

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