The HTML DOM Input Radio form property is used for returning the form reference that contains the given input radio button. If the radio button is outside the form then it will simply return NULL. This property is read-only.

Syntax

Following is the syntax for input radio form property ?

radioObject.form

Example

Let us look at an example for the Input radio form property.

Input radio form Property

Get the form id by clicking on the below button

Output

This will produce the following output ?

On clicking the GET FORM button ?

In the above example ?

We have first created an input element inside a form with type="radio", name="fruits", id="Mango". The form has the id attribute value set to "FORM1" ?

We have then created a button GET FORM that will execute the formId() method when clicked by the user ?

GET FORM

The formId() method uses the getElementById() method to get the input field with type radio and gets the id property of the form object that contains the radio button. It then assigns this value to variable P and displays in the paragraph with id "Sample" using its innerHTML property ?

function formId() {
   var P=document.getElementById("Mango").form.id;
   document.getElementById("Sample").innerHTML = "The id of the form containing the password field is: "+P ;
}