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length property (form, keygen, select)

Browser support:
Returns the number of form controls in a form element or the number of options in a select or keygen element.
For the list of form controls, see the page for the form element.


You can find the related objects in the Supported by objects section below.
This property is read-only.

Possible values:

Integer that represents the number of objects.
Default: this property has no default value.

Example HTML code 1:

This example illustrates the use of the length property:
    <script type="text/javascript">
        function GetLength () {
            var elemLength = document.getElementById ("myForm").length;
            alert ("There are " + elemLength + " form controls in the form.");
    <form id="myForm">
        <input type="radio" name="sex" id="radio_female" value="female" checked="checked"/> <label for="radio_female">female</label>
        <br />
        <input type="radio" name="sex" id="radio_male" value="male" /> <label for="radio_male">male</label>
        <br /><br />
        <input type="submit" value="Register" disabled="disabled" />
    <br /><br />
    <button onclick="GetLength ();">Get form length!</button>
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