https://community.adobe.com/t5/Illustrator/auto-close-alert-message/td-p/9398258

CloseAlert

customAlert('Hello', 3, 'This is a test - Will close in 3 seconds')
customAlert('Hello', 0, 'This is a test - Will not close automatically')

function customAlert(message, delaySeconds, title){
    title = title || 'Alert';
    var alertWindow = new Window('palette', title);
    var control_text = alertWindow.add('edittext', [0, 0, 500, 200], message, {multiline: true});
   
    if(delaySeconds == 0){
        var control_close = alertWindow.add('button', undefined, 'Close');       
        control_close.onClick = function(){
            if(alertWindow){
                alertWindow.hide();
            }
        };
    }

    alertWindow.show();
    alertWindow.update();
   
    if(delaySeconds > 0){
        $.sleep(delaySeconds * 1000);
        alertWindow.hide();
        alertWindow = null;
    }  
}