jQuery - Check if any specific radio buttons are checked

Question

jQuery

$('input').change(function() {

  $('input:radio').prop('disabled', true);
  $('.answer-detail').show();

  $(this).next('label').addClass('correct');

  var correctAnswers = ("#answer1d", "#answer2c", "#answer3c");

  if (!$(correctAnswers).is(":checked")) {
    alert('Nothing is checked!');
  } else {
    alert('One of the radio buttons is checked!');
  }

});

HTML

<p>1: <span>What colour is the snowflake?</span></p>
<input class="answer" id="answer1a" type="radio" name="answer1" value="answer1a" /><label for="answer1a">Monochrome</label>
<input class="answer" id="answer1b" type="radio" name="answer1" value="answer1b" /><label for="answer1b">White</label>
<input class="answer" id="answer1c" type="radio" name="answer1" value="answer1c" /><label for="answer1c">Pantone 000C</label>
<input class="answer" id="answer1d" type="radio" name="answer1" value="answer1d" /><label for="answer1d">None of the above</label> 

I want to check if any of the 'correctAnswers' checkboxes are checked.

At the moment if I selected 'answer1d' it returns:-

alert('One of the radio buttons is checked!');

Any idea how I can loop through each answer and see if either are checked?

Answer 1

You could change correctAnswers to an array of id attributes, then use the .indexOf() method to check if the checked element's id is in the array:

Updated Example

var correctAnswers = ["answer1d", "answer2c", "answer3c"];

if (correctAnswers.indexOf(this.id) > -1) {
  alert('One of the radio buttons is checked!');
} else {
  alert('Nothing is checked!');
}

Answer 2

You can filter checked elements along with .length to get checked elements count:

var correctAnswers = ("#answer1d,#answer2c,#answer3c");
if(!$(correctAnswers).filter(':checked').length) {
   alert('Nothing is checked!');
}
else {
  alert('One of the radio buttons is checked!');
}