JavaScript: The Definitive Guide, Fourth Edition

Name

Checkbox — a graphical checkbox

Availability

JavaScript 1.0; enhanced in JavaScript 1.1

Inherits from/Overrides

Inherits from Input, HTMLElement

Synopsis

A single Checkbox element with a unique name may be referenced in either of these ways:

                  form.checkbox_name
                  form.elements[i]

When a form contains a group of checkboxes with the same name, they are placed in an array and may be referenced as follows:

                  form.checkbox_name[j] form.checkbox_name.length 

Properties

Checkbox inherits properties from Input and HTMLElement and defines or overrides the following:

checked

A read/write boolean property. If the checkbox is checked, the checked property is true. If the checkbox is not checked, checked is false.

If you set checked to true, the checkbox appears checked. Similarly, if you set this property to false, the checkbox appears unchecked. Note that setting the checked property does not cause the Checkbox element’s onclick event handler to be invoked.

defaultChecked

A read-only boolean that specifies the initial state of the checkbox. It is true if the checkbox is initially checked -- i.e., if the checked attribute appears in the checkbox’s HTML <input> tag. If this attribute does not appear, the checkbox is initially unchecked and defaultChecked is false.

value

A read/write string property that specifies the text passed to the web server if the checkbox is checked when the form is submitted. The initial value of value is specified by the value attribute of the checkbox’s HTML <input> ...