javascript - Show warning message before close window in Java Script

Question

posted Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

I've try this:

<body onunload="LogoutNoAsk();"> </body>

and the function is:

function LogoutNoAsk()
{
    alert("Please press the Logout button to logout.");
    parent.close();

}

When I press close which is the 'X' button on the top right of the window, it close straightaway without the warning message. What's wrong?

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1 Reply

深蓝 · Answer 1 · 2021-10-17T02:58:03+0000

You're actually wanting to use the onbeforeunload event which allows you to block the close event.

See the MDN reference for details, but the code required would be:

window.onbeforeunload = function(e) {
    return 'Please press the Logout button to logout.';
};