onunload Attribute

Where to use the onunload Attribute

• As Type Script:
  onunload is declared on the element: body

Description

The onunload attribute may be used on the body element to specify script to be executed on leaving the page. Please do not irritate your visitors by using this attribute to, for example, open pop-up windows when they leave a page! [My personal opinion is that the onunload handler should not do anything which visibly or audibly affects the user in any way!]

See also the onload attribute.

If you use this attribute (or any attributes of Type Script) the MIME type of the scripting language used should always be provided in a Content-Script-Type HTTP header.

It is good practice not to use these attributes, however, and instead to include external scripts (via script elements) which add any handlers unobtrusively. This makes code more self-contained and also the XHTML is easier to maintain if it doesn't contain any events attributes.