:checked Selector

checked ( ) version added: 1.0

Description: Matches all elements that are checked or selected.

The :checked selector works for checkboxes, radio buttons, and select elements. For select elements only, use the :selected selector.

Examples:

Example: Determine how many input elements are checked. 

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>css demo</title>

  <style>

  div {
    color: red;
  }

  </style>

  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
  

<form>
  <p>
    <input type="checkbox" name="newsletter" value="Hourly" checked="checked">

    <input type="checkbox" name="newsletter" value="Daily">
    <input type="checkbox" name="newsletter" value="Weekly">

    <input type="checkbox" name="newsletter" value="Monthly" checked>
    <input type="checkbox" name="newsletter" value="Yearly">
  </p>
</form>
<div></div>

<script>

var countChecked = function() {
  var n = $( "input:checked" ).length;
  $( "div" ).text( n + (n === 1 ? " is" : " are") + " checked!" );
};
countChecked();

$( "input[type=checkbox]" ).on( "click", countChecked );

</script>

  
</body>
</html>

Demo:

Example: Identify the checked radio input. 

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>css demo</title>

  <style>

  input, label {
    line-height: 1.5em;
  }

  </style>

  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
  

<form>
  <div>
    <input type="radio" name="fruit" value="orange" id="orange">
    <label for="orange">orange</label>
  </div>
  <div>
    <input type="radio" name="fruit" value="apple" id="apple">
    <label for="apple">apple</label>
  </div>
  <div>
    <input type="radio" name="fruit" value="banana" id="banana">
    <label for="banana">banana</label>
  </div>
  <div id="log"></div>
</form>

<script>

$( "input" ).on( "click", function() {
  $( "#log" ).html( $( "input:checked" ).val() + " is checked!" );
});

</script>

  
</body>
</html>

Demo: