Navigator 2.0, Internet Explorer 3.0
The onblur() event handler of a form element is invoked by the web browser when the user transfers keyboard focus away from that form element. Calling blur() to remove focus from an element does not invoke onblur() for that object. Note, however, that calling focus() to transfer focus to some other element will cause the onblur() event handler to be invoked for whatever element currently has the focus.
The onblur() event handler is available for all form elements except the Hidden element. For Navigator 2.0 and 3.0 on Unix platforms, however, it is only invoked for the text-entry elements: Text, Textarea, Password and FileUpload. Note that in Navigator 3.0, the Window object also defines an onblur() event handler.