Using JavaScript to Check a Radio Button

We can use JavaScript to check a radio button by making use of the getElementById() method along with targeting the checked property value. We simply need to change the checked property value of the radio button to true. Here is how we can do this:

document.getElementById("radioButton").checked = true;

Let’s see an example of this below.

Lets say we have the following HTML:

<div id="div1">
  <p>Select your favorite mode of transportation:</p>
  <input type="radio" id="bike" name="transport" value="Bike"> <label for="bike">Bike</label><br>
  <input type="radio" id="car" name="transport" value="Car"> <label for="car">Car</label><br>
  <input type="radio" id="bus" name="transport" value="Bus"> <label for="bus">Bus</label><br>
  <input type="radio" id="train" name="transport" value="Train"> <label for="train">Train</label><br>
  <input type="radio" id="boat" name="transport" value="Boat"> <label for="boat">Boat</label><br>
  <input type="radio" id="airplane" name="transport" value="Airplane"> <label for="airplane">Airplane</label><br>
</div>
  <div id="click-me" onclick="setRadio()">Set the radio button Airplane to checked</div><br>
</div>

In this example, we will use the onclick event to call a function setRadio() which we will create below.

The setRadio() function will simply set the last radio button, Airplane, to be checked.

Here is our function using JavaScript:

function setRadio(){
  document.getElementById("airplane").checked = true;
}; 

Let’s try this out below:

Code Output:

Full Code:

<div id="div1">
  <p>Select your favorite mode of transportation:</p>
  <input type="radio" id="bike" name="transport" value="Bike"> <label for="bike">Bike</label><br>
  <input type="radio" id="car" name="transport" value="Car"> <label for="car">Car</label><br>
  <input type="radio" id="bus" name="transport" value="Bus"> <label for="bus">Bus</label><br>
  <input type="radio" id="train" name="transport" value="Train"> <label for="train">Train</label><br>
  <input type="radio" id="boat" name="transport" value="Boat"> <label for="boat">Boat</label><br>
  <input type="radio" id="airplane" name="transport" value="Airplane"> <label for="airplane">Airplane</label><br>
</div>
  <div id="click-me" onclick="setRadio()">Set the radio button Airplane to checked</div><br>
</div>

<script>

function setRadio(){
  document.getElementById("airplane").checked = true;
}; 

</script>

To uncheck a button using JavaScript, we simply need to set the checked attribute to false.

Using JavaScript to Get the Value of a Radio Button

We can use JavaScript to get the value of a radio button using the querySelector() method.

document.querySelector('input[name="radio1"]:checked').value;

Lets say we have the following HTML:

<div id="div2">
  <p>Select your favorite mode of transportation:</p>
  <input type="radio" id="bike1" name="transport" value="Bike"><label for="bike1">Bike</label><br>
  <input type="radio" id="car1" name="transport" value="Car"><label for="car1">Car</label><br>
  <input type="radio" id="bus1" name="transport" value="Bus"><label for="bus1">Bus</label><br>
  <input type="radio" id="train1" name="transport" value="Train" checked><label for="train1">Train</label><br>
  <input type="radio" id="boat1" name="transport" value="Boat"><label for="boat1">Boat</label><br>
  <input type="radio" id="airplane1" name="transport" value="Airplane"><label for="airplane1">Airplane</label><br>
</div>

In this example, the checked radio button to start will be the Train option. We can use our code above to get this value using JavaScript.

Here is the jQuery code we will need:

var selectedRadioButton = document.querySelector('#div2 input[name="transport"]:checked').value;

Try it out below by selecting a radio button and then clicking the button below to see what radio button is checked:

Code Output:

Full Code:

<div id="div2">
  <p>Select your favorite mode of transportation:</p>
  <input type="radio" id="bike1" name="transport" value="Bike"> <label for="bike1">Bike</label><br>
  <input type="radio" id="car1" name="transport" value="Car"> <label for="car1">Car</label><br>
  <input type="radio" id="bus1" name="transport" value="Bus"> <label for="bus1">Bus</label><br>
  <input type="radio" id="train1" name="transport" value="Train" checked> <label for="train1">Train</label><br>
  <input type="radio" id="boa1t" name="transport" value="Boat"> <label for="boat1">Boat</label><br>
  <input type="radio" id="airplane1" name="transport" value="Airplane"> <label for="airplane1">Airplane</label><br>
</div>
  <div id="click-me" onclick="selectedRadio()">Check which radio button is selected with JavaScript</div>
  <div id="results"></div>
</div>

<script>

function selectedRadio(){
  var selectedRadioButton = document.querySelector('#div2 input[name="transport"]:checked').value;
  document.getElementById("results").textContent = selectedRadioButton;
}; 

</script>

Hopefully this article has been useful to help you understand how to use JavaScript to check a radio button.