Display warning when losing a tab in edit mode

[srg]

Hi all,

    I have a requirement that, if any datagrid is in edit mode it need to display warning with popup with the message "Unsaved data will be lost. Do you want to proceed".

Note: It should not be confirm navigation what we see on chrome.

here i am using this code.

window.addEventListener('beforeunload', function(e) {
     var confirmationMessage = "Unsaved data will be lost. Do you want to proceed?";
     (e || window.event).returnValue = confirmationMessage;
});

But it is showing confirm navigation. not the popup what ineed . can anyone give me a solution ..

Thanks in advance..
Swetha.