Jquery Tutorial: How can I know which radio button is selected via jQuery?

Jquery tutorial will help, how to know which radio button is selected via jquery. let go though tutorial of jquery.

 To get the value of the selected radioName item of a form with id myForm:

$('input[name=radioName]:checked', '#myForm').val()

Here's an example:

Script

$('#myForm input').on('change', function() {
   alert($('input[name=radioName]:checked', '#myForm').val()); 
});

Form

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="myForm">
  <input type="radio" name="radioName" value="1" /> 1 <br />
  <input type="radio" name="radioName" value="2" /> 2 <br />
  <input type="radio" name="radioName" value="3" /> 3 <br />
</form>

2.Second Method  Using Submit Button

 $(function(){
     $("#submit").click(function(){      
         alert($('input:radio:checked').val());
     });
  });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<table>
       <tr>
         <td>Sales Promotion</td>
         <td><input type="radio" name="q12_3" value="1">1</td>
         <td><input type="radio" name="q12_3" value="2">2</td>
         <td><input type="radio" name="q12_3" value="3">3</td>
         <td><input type="radio" name="q12_3" value="4">4</td>
         <td><input type="radio" name="q12_3" value="5">5</td>
      </tr>
    </table>
<button id="submit">submit</button>