<input type="radio"> - HTML: HyperText Markup Language 编辑

<input> elements of type radio are generally used in radio groups—collections of radio buttons describing a set of related options. Only one radio button in a given group can be selected at the same time. Radio buttons are typically rendered as small circles, which are filled or highlighted when selected.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

They are called radio buttons because they look and operate in a similar manner to the push buttons on old-fashioned radios, such as the one shown below.

Note: Checkboxes are similar to radio buttons, but with an important distinction: radio buttons are designed for selecting one value out of a set, whereas checkboxes let you turn individual values on and off. Where multiple controls exist, radio buttons allow one to be selected out of them all, whereas checkboxes allow multiple values to be selected.

Value	A DOMString representing the value of the radio button.
Events	change and input
Supported common attributes	checked, value and required
IDL attributes	checked and value
Methods	select()

Value

The value attribute is a DOMString containing the radio button's value. The value is never shown to the user by their user agent. Instead, it's used to identify which radio button in a group is selected.

Defining a radio group

A radio group is defined by giving each of radio buttons in the group the same name. Once a radio group is established, selecting any radio button in that group automatically deselects any currently-selected radio button in the same group.

You can have as many radio groups on a page as you like, as long as each has its own unique name.

For example, if your form needs to ask the user for their preferred contact method, you might create three radio buttons, each with the name property set to contact but one with the value email, one with the value phone, and one with the value mail. The user never sees the value or the name (unless you expressly add code to display it).

The resulting HTML looks like this:

<form>
  <p>Please select your preferred contact method:</p>
  <div>
    <input type="radio" id="contactChoice1"
     name="contact" value="email">
    <label for="contactChoice1">Email</label>

    <input type="radio" id="contactChoice2"
     name="contact" value="phone">
    <label for="contactChoice2">Phone</label>

    <input type="radio" id="contactChoice3"
     name="contact" value="mail">
    <label for="contactChoice3">Mail</label>
  </div>
  <div>
    <button type="submit">Submit</button>
  </div>
</form>

Here you see the three radio buttons, each with the name set to contact and each with a unique value that uniquely identifies that individual radio button within the group. They each also have a unique id, which is used by the <label> element's for attribute to associate the labels with the radio buttons.

You can try out this example here:

Data representation of a radio group

When the above form is submitted with a radio button selected, the form's data includes an entry in the form contact=value. For example, if the user clicks on the "Phone" radio button then submits the form, the form's data will include the line contact=phone.

If you omit the value attribute in the HTML, the submitted form data assigns the value on to the group. In this scenario, if the user clicked on the "Phone" option and submitted the form, the resulting form data would be contact=on, which isn't helpful. So don't forget to set your value attributes!

Note: If no radio button is selected when the form is submitted, the radio group is not included in the submitted form data at all, since there is no value to report.

It's fairly uncommon to actually want to allow the form to be submitted without any of the radio buttons in a group selected, so it is usually wise to have one default to the checked state. See Selecting a radio button by default below.

Let's add a little bit of code to our example so we can examine the data generated by this form. The HTML is revised to add a <pre> block to output the form data into:

<form>
  <p>Please select your preferred contact method:</p>
  <div>
    <input type="radio" id="contactChoice1"
           name="contact" value="email">
    <label for="contactChoice1">Email</label>
    <input type="radio" id="contactChoice2"
           name="contact" value="phone">
    <label for="contactChoice2">Phone</label>
    <input type="radio" id="contactChoice3"
           name="contact" value="mail">
    <label for="contactChoice3">Mail</label>
  </div>
  <div>
    <button type="submit">Submit</button>
  </div>
</form>
<pre id="log">
</pre>

Then we add some JavaScript to set up an event listener on the submit event, which is sent when the user clicks the "Submit" button:

var form = document.querySelector("form");
var log = document.querySelector("#log");

form.addEventListener("submit", function(event) {
  var data = new FormData(form);
  var output = "";
  for (const entry of data) {
    output = output + entry[0] + "=" + entry[1] + "\r";
  };
  log.innerText = output;
  event.preventDefault();
}, false);

Try this example out and see how there's never more than one result for the contact group.

Additional attributes

In addition to the common attributes shared by all <input> elements, radio inputs support the following attributes:

Attribute	Description
checked	A Boolean indicating whether or not this radio button is the default-selected item in the group
value	The string to use as the value of the radio when submitting the form, if the radio is currently toggled on

checked

A Boolean attribute which, if present, indicates that this radio button is the default selected one in the group.

Unlike other browsers, Firefox by default persists the dynamic checked state of an <input> across page loads. Use the autocomplete attribute to control this feature.

value

The value attribute is one which all <input>s share; however, it serves a special purpose for inputs of type radio: when a form is submitted, only radio buttons which are currently checked are submitted to the server, and the reported value is the value of the value attribute. If the value is not otherwise specified, it is the string on by default. This is demonstrated in the section Value above.

Using radio inputs

We already covered the fundamentals of radio buttons above. Let's now look at the other common radio-button-related features and techniques you may need to know about.

Selecting a radio button by default

To make a radio button selected by default, you include checked attribute, as shown in this revised version of the previous example:

<form>
  <p>Please select your preferred contact method:</p>
  <div>
    <input type="radio" id="contactChoice1"
     name="contact" value="email" checked>
    <label for="contactChoice1">Email</label>

    <input type="radio" id="contactChoice2"
     name="contact" value="phone">
    <label for="contactChoice2">Phone</label>

    <input type="radio" id="contactChoice3"
     name="contact" value="mail">
    <label for="contactChoice3">Mail</label>
  </div>
  <div>
    <button type="submit">Submit</button>
  </div>
</form>

In this case, the first radio button is now selected by default.

Note: If you put the checked attribute on more than one radio button, later instances will override earlier ones; that is, the last checked radio button will be the one that is selected. This is because only one radio button in a group can ever be selected at once, and the user agent automatically deselects others each time a new one is marked as checked.

Providing a bigger hit area for your radio buttons

In the above examples, you may have noticed that you can select a radio button by clicking on its associated <label> element, as well as on the radio button itself. This is a really useful feature of HTML form labels that makes it easier for users to click the option they want, especially on small-screen devices like smartphones.

Beyond accessibility, this is another good reason to properly set up <label> elements on your forms.

Validation

Radio buttons don't participate in constraint validation; they have no real value to be constrained.

Styling radio inputs

The following example shows a slightly more thorough version of the example we've seen throughout the article, with some additional styling, and with better semantics established through use of specialized elements. The HTML looks like this:

<form>
  <fieldset>
    <legend>Please select your preferred contact method:</legend>
    <div>
      <input type="radio" id="contactChoice1"
       name="contact" value="email" checked>
      <label for="contactChoice1">Email</label>

      <input type="radio" id="contactChoice2"
       name="contact" value="phone">
      <label for="contactChoice2">Phone</label>

      <input type="radio" id="contactChoice3"
       name="contact" value="mail">
      <label for="contactChoice3">Mail</label>
    </div>
    <div>
      <button type="submit">Submit</button>
    </div>
  </fieldset>
</form>

There's not much new to note here except for the addition of <fieldset> and <legend> elements, which help to group the functionality nicely and in a semantic way.

The CSS involved is a bit more significant:

html {
  font-family: sans-serif;
}

div:first-of-type {
  display: flex;
  align-items: flex-start;
  margin-bottom: 5px;
}

label {
  margin-right: 15px;
  line-height: 32px;
}

input {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;

  border-radius: 50%;
  width: 16px;
  height: 16px;

  border: 2px solid #999;
  transition: 0.2s all linear;
  margin-right: 5px;

  position: relative;
  top: 4px;
}

input:checked {
  border: 6px solid black;
}

button,
legend {
  color: white;
  background-color: black;
  padding: 5px 10px;
  border-radius: 0;
  border: 0;
  font-size: 14px;
}

button:hover,
button:focus {
  color: #999;
}

button:active {
  background-color: white;
  color: black;
  outline: 1px solid black;
}

Most notable here is the use of the appearance property (with prefixes needed to support some browsers). By default, radio buttons (and checkboxes) are styled with the operating system's native styles for those controls. By specifying appearance: none, you can remove the native styling altogether, and create your own styles for them. Here we've used a border along with border-radius and a transition to create a nice animating radio selection. Notice also how the :checked pseudo-class is used to specify the styles for the radio button's appearance when selected.

Compatibility note: If you wish to use the appearance property, you should test it very carefully. Although it is supported in most modern browsers, its implementation varies widely. In older browsers, even the keyword none does not have the same effect across different browsers, and some do not support it at all. The differences are smaller in the newest browsers.

Notice that when clicking on a radio button, there's a nice, smooth fade out/in effect as the two buttons change state. In addition, the style and coloring of the legend and submit button are customized to have strong contrast. This might not be a look you'd want in a real web application, but it definitely shows off the possibilities.

Specifications

Specification	Status
HTML Living Standard The definition of '<input type="radio">' in that specification.	Living Standard
HTML5 The definition of '<input type="radio">' in that specification.	Recommendation

Browser compatibility

BCD tables only load in the browser

See also

• <input> and the HTMLInputElement interface that implements it.
• RadioNodeList: the interface that describes a list of radio buttons
• Compatibility of CSS properties