getting class name of check box when it checked only
<p>i have any html code which contains two check boxes and having class names like this</p>

<pre><code>&lt;p class="text"&gt;
                &lt;input type="checkbox" value="Yes" id="ques11" name="radiobutton" class="option_1" /&gt;
                &lt;label for="ques11"&gt;True&lt;/label&gt;
                &lt;span class="hide" id="ans1"&gt;Answer: True&lt;/span&gt;
                &lt;span id="rite11" class="hide"&gt;&lt;img class="imgsize" src="images/ans_correct.png"/&gt;&lt;/span&gt;
                &lt;span id="wrong11" class="hide"&gt;&lt;img class="imgsize" src="images/ans_wrong.png"/&gt;&lt;/span&gt; &lt;/p&gt;

            &lt;p class="text"&gt;
                &lt;input type="checkbox" value="No" id="ques12" name="radiobutton" class="option_2" /&gt;
                &lt;label for="ques12"&gt;False&lt;/label&gt;
                &lt;span id="rite12" class="hide"&gt;&lt;img class="imgsize" src="images/ans_correct.png"/&gt;&lt;/span&gt;
                &lt;span id="wrong12" class="hide"&gt;&lt;img class="imgsize" src="images/ans_wrong.png"/&gt;&lt;/span&gt; &lt;/p&gt;
</code></pre>

<p>i have written script to get which chekbox is checked </p>

<pre><code> $('input[type="checkbox"]').each(function(){
  var quesNo = this).closest("div[id^='questionsNo_']").attr('id').split('_');
 var chapterId = quesNo[1]; 
 var questionId = quesNo[2];
 var optionId = $(this).attr('class').split('_')[1];
 ...
</code></pre>

<p>in var optionId  i want to get the checked one  like,if i checked the 1st check box ,i want to get '1' value from 'option_1' ,suppose i have checked second check box ,i want to get 2 from 'option_2'.how to get the value of checked checkbox only .</p>