[Chapter 21] Reference: Window.onfocus()
Author: David Flanagan
Date: Fri Aug 29 11:21:20 1997

#

| Chapter 21 JavaScript Reference |

# Window.onfocus() Handler

## Name

Window.onfocus() Handler---invoked when window is given focus

## Availability

Navigator 3.0

## Synopsis

    <BODY    a definition of the handler
        [ onFocus="JavaScript statements" ]
            ...
    >
    <FRAMESET    another way to define the handler
        [ onFocus="JavaScript statements" ]
           ...
    >
    window.onfocus=handler-func defining the handler directly
    window.onfocus(); an explicit invocation of the handler

## Description

`onfocus()` is an event handler invoked by the browser when a top-level browser window is given the input focus, either because the user has switched to the browser window, or because focus was transferred to the window with the Window `focus()` or `blur()` methods.

The `onfocus()` event handler can be defined in HTML by specifying the `onFocus` attribute of the `<BODY>` or `<FRAMESET>` tag of the document or frameset that occupies the top-level window. The value of this attribute may be any number of JavaScript statements, separated by semicolons. This event handler may also be defined by assigning a function to the `onfocus` property of the Window object.

## Usage

If your web page does some sort of animation, you might use the `onfocus()` event handler to start the animation and the `onblur()` handler to stop it, so that it only runs while the user is paying attention to the window.

## See Also

"Window", "Window.blur()", "Window.focus()", "Window.onblur()"

Window.onerror() |  | Window.onload()