The body tag of a webpage contains onload events. These events occur when important elements in the page need to load. They are compatible with elements in the DOM, such as web cookies and images. Onload events can be handled by adding a listener to the event target. You can add onload events to multiple pages. This allows you to write as many handlers for the event target as you wish.
To write multiple onload handlers in a single page, the first one must be included in the body code of the page. If the first one fails, a second one can be used to replace it. While both methods are workable, one is better. The second method is a good choice if you have a small website, but you may find yourself using it a lot.
Beforeunload handlers on the other hand are similar to onload handlers but ask for confirmation before closing the page or exiting the page. By returning a non-empty string, this event counts as an error. Browsers used to display a message asking users to confirm their actions. However, this message may still be displayed in some browsers.
Adding a listener to an onload event is an alternative to writing the same function repeatedly. Onload events handle the loading process and make sure everything is ready for users. There are limitations. The method addEventListener() is not supported in Internet Explorer 8 or earlier versions. To add a listener, you can use the onload() method.
Another important advantage of adding an onload event handler to an element is that it does not propagate. This means that handlers for parent elements won’t receive a notification when a child element gains focus. Instead, the handlers can safely reference the form elements within the body. It’s possible to intercept other events on the same page, since it’s not necessary interrupt the event.