Opera JavaScript Flaw--Radio Buttons

This page demonstrates an apparent flaw in the Opera 3.60 browser. This page is a simplified example based on the original application where the flaw was discovered.

This flaw first appeared in version 3.0 of the Opera browser, was apparently fixed in a later version, and reappeared by version 3.60.

The example below includes a form containing a pair of radio buttons and a JavaScript fragment intended to determine whether one of the buttons is checked. The JavaScript fragment fails in Opera 3.60.

Form

The form in this section has a pair of radio buttons. In the Results section below, a JavaScript fragment should indicate which button is checked. When this page is viewed in Opera 3.60, however, the JavaScript code fails.

(Note that the page will not be updated if you select a different radio button.)

The form is defined like this:


<FORM NAME="frmTest">
    <INPUT TYPE=radio NAME="rbtnRadioTest" VALUE="One" CHECKED OnClick="0">One
    <INPUT TYPE=radio NAME="rbtnRadioTest" VALUE="Two" OnClick="0">Two
</FORM>

Source

Here is a view of the JavaScript source. The script's results should be displayed in the next section.


<SCRIPT LANGUAGE="JavaScript">

    // <!--

    if (document.frmTest.rbtnRadioTest[0].checked == true)
        document.write ("Radio button 'One' is checked.");
    else
        document.write ("Radio button 'One' is not checked.");

    // -->

</SCRIPT>

Results

You should see a message generated by JavaScript below, saying, "Radio button 'One' is/is not checked." In earlier versions of Opera 3.x, however, the script fails and no message appears. In Opera 3.60, the script erroneously reports that the radio button is not checked.

Message generated by JavaScript:

Discovered By

This flaw was discovered by Charles L. Taylor, who also prepared this example.