Navigator 2.0, Internet Explorer 3.0; enhanced in Navigator 3.0
form.radio_name[j] form.radio_name.length form.elements[i][j] form.elements[i].length
A read/write Boolean value that specifies whether the button is checked or not.
A read-only Boolean that specifies the initial state of the radio button. May be specified with the HTML CHECKED attribute.
A read-only reference to the Form object that contains the Radio element.
A read-only string, set by the HTML NAME attribute, that specifies the name of the Radio button.
A read-only string that specifies the type of this form element. For Radio elements, it has the value "radio". Available in Navigator 3.0 and later.
A read/write string, initially set by the HTML VALUE attribute, that specifies the value returned by the Radio button if it is selected when the form is submitted.
A Radio element is created with a standard HTML <INPUT> tag, with the addition of the new onClick attribute. Radio elements are created in groups by specifying multiple <INPUT> tags that have the same NAME attribute.
The Radio element represents a single graphical radio button in an HTML form. A radio button is one button in a group of buttons that represent mutually exclusive choices. When one button is selected, the previously selected button becomes deselected.
You can examine the checked property to determine the state of the button, and you can also set this property to select or deselect the button. Note that setting checked changes the graphical appearance of the button, but does not invoke the onClick event handler. The initial value of the checked property, and the value of the defaultChecked property are determined by the CHECKED attribute. Only one Radio element in a group may contain this attribute--it sets the checked and defaultChecked properties true for that element and false for all other Radio buttons in the group. If none of the elements have the CHECKED attribute, then the first one in the group will be checked (and defaultChecked) by default.
Note that the text that appears next to a Radio button is not part of the Radio element itself, and must be specified externally to the Radio's HTML <INPUT> tag.
Radio elements are used in groups of mutually exclusive options, and each member of the group is given the same NAME attribute (the shared name defines the members of the group). So if the shared name of a group of Radio elements in form f is "opts", then f.opts is an array of Radio elements, and f.opts.length is the number of elements in the array.
Unfortunately, in Navigator 2.0, there is a bug in how Radio elements in a group are assigned to an array. See the "Bugs" section for details.
You can set the VALUE attribute or the value property of a Radio element to specify the string that will be passed to the server if the Radio element is checked when the form is submitted. Each Radio element in a group should specify a distinct value so that a script on the server can determine which one was checked when the form was submitted.
Radio elements can be used to present the user with a list of multiple, mutually exclusive, options. Use the Checkbox element to present a single option or to present a list of options that are not mutually exclusive.
At least some versions of Navigator do not correctly select the first radio button in a group when no buttons in the group have the CHECKED attribute specified. Therefore you should always explicitly specify the CHECKED attribute for one default selection in every radio button group.