Alert may refer to any of the following:
window.alert("This is an alert!");
alert("This is an alert!");
2. In general, an alert box, also called an alert dialog or alert window. It is a small window that pops up providing information to the user and typically includes an OK button, and sometimes a Cancel button.
Error messages and general information are commonly displayed in alert boxes, as it calls attention to itself and makes the user click a button to hide the message. The Windows operating system, along with third-party applications, and web pages are sources for alert boxes.