Navigator 2.0, Internet Explorer 3.0
element.onfocus
The onfocus() event handler of a form element is invoked by the web browser when the user transfers the keyboard focus to that element. Note that it is not invoked when focus is programmatically transfered with the focus() method.
The onfocus() event handler is a function defined through the onFocus attribute of the HTML tag that defined the element. The value of this attribute is a string that may contain any number of JavaScript statements, separated by semicolons. In Navigator 3.0, the onfocus() event handler may also be defined by assigning a function directly to the onfocus property of the element.
The onfocus() 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 onfocus() event handler.