how to understand radio button is checked or not in jquery code example

Example 1: check radio button is checked jquery

$(document).ready(function(){
  $('#submit_button').click(function() {
    if (!$("input[name='name']:checked").val()) {
       alert('Nothing is checked!');
        return false;
    }
    else {
      alert('One of the radio buttons is checked!');
    }
  });
});

Example 2: How can I know which radio button is selected via jQuery

if ($('input[name="radioName"]:checked', '#myForm').length) {
	//Yes, it's checked!
}