How to listen to when a checkbox is checked in Jquery

Use the change() event, and the is() test:

$('input:checkbox').change(
    function(){
        if ($(this).is(':checked')) {
            alert('checked');
        }
    });

I’ve updated the above, to the following, because of my silly reliance on jQuery (in the if) when the DOM properties would be equally appropriate, and also cheaper to use. Also the selector has been changed, in order to allow it to be passed, in those browsers that support it, to the DOM’s document.querySelectorAll() method:

$('input[type=checkbox]').change(
    function(){
        if (this.checked) {
            alert('checked');
        }
    });

For the sake of completion, the same thing is also easily possible in plain JavaScript:

var checkboxes = document.querySelectorAll('input[type=checkbox]'),
    checkboxArray = Array.from( checkboxes );

function confirmCheck() {
  if (this.checked) {
    alert('checked');
  }
}

checkboxArray.forEach(function(checkbox) {
  checkbox.addEventListener('change', confirmCheck);
});

---

References:

• JavaScript:
  • Array.from().
  • Array.prototype.forEach().
  • document.querySelectorAll().
  • EventTarget.addEventListener().
• jQuery:
  • :checked.
  • change().
  • is().