JavaScript: Overriding alert()

I have faced a requirement to show a default message along with the actual alert messages. This is how I managed to do it.

    const actualAlertFunc = window.alert;
    window.alert = function(msg) {
         actualAlertFunc('some default message '+ msg);
    }

I have tested it on chrome. I am not sure whether its a good practise, but it serves the purpose.