onreadystatechange Property
Returns or sets a Variant that represents the value of the onreadystatechange attribute that is the name of the script to run when the onreadystatechange event fires.
expression.onreadystatechange
expression Required. An expression that returns one of the objects in the Applies To list.
Example
The following example sets the onreadystatechange attribute for the first LINK element in the active document.
Dim objLink As FPHTMLLinkElement
Set objLink = ActiveDocument.all.tags("link").Item(0)
objLink.onreadystatechange = "script()"