13-6.txt

Javascript语言开发经典教程开发

<!--  This file implements a navigation bar, designed to go in a frame at
      the bottom of a window. Include it in a frameset like the following:

        <frameset rows="*,75">
        <frame src="about:blank">
        <frame src="navigation.html">
        </frameset>
-->

<SCRIPT>
// The function is invoked by the Back button in our navigation bar.
function go_back() 
{
    // First, clear the URL entry field in our form.
    document.navbar.url.value = "";

    // Then use the History object of the main frame to go back.
    parent.frames[0].history.back();

    // Wait a second, and then update the URL entry field in the form
    // from the location.href property of the main frame. The wait seems
    // to be necessary to allow the location.href property to get in sync.
    setTimeout("document.navbar.url.value = parent.frames[0].location.href;",
               1000);
}

// This function is invoked by the Forward button in the navigation bar.
// It works just like the one above.
function go_forward()
{
    document.navbar.url.value = "";
    parent.frames[0].history.forward();
    setTimeout("document.navbar.url.value = parent.frames[0].location.href;",
               1000);
}

// This function is invoked by the Go button in the navigation bar, and also
// when the form is submitted (when the user hits the Return key).
function go_to()
{
    // Just set the location property of the main frame to the URL
    // that the user typed in.
    parent.frames[0].location = document.navbar.url.value;
}
</SCRIPT>

<!-- Here's the form, with event handlers that invoke the functions above. -->
<FORM NAME="navbar" onSubmit="go_to(); return false">
<INPUT TYPE="button" VALUE="Back"  onClick="go_back();">
<INPUT TYPE="button" VALUE="Forward"  onClick="go_forward()">
URL:
<INPUT TYPE="text" NAME="url" SIZE=50">
<INPUT TYPE="button" VALUE="Go" onClick="go_to()">
</FORM>