title: Check boxes: Allow for only one check box to be click at a time
body: <p>I am currently working with check boxes and displaying values based on the values chosen. Almost everything is working in exception that i have to check boxes for <code>method of shipping</code>. Right now the user can select two ways and this is an issue. Is there a way to only allow one check box to be checked for <code>method of shipping</code>? <a href="http://webprolearner2346.zxq.net/bike_calculator/" rel="nofollow">EXAMPLE</a></p>
  
  <p><strong>JS</strong></p>
  
  <pre><code>&lt;script&gt;
  function check_value(currentElement, val, id, type) {
      var el = document.getElementById("imgBox" + id);
      if (val &gt; 0 &amp;&amp; val &lt; 4) { //will trigger when [1,2,3]
  
          if(currentElement.checked)
          {
              el.src = "images/" + type + val + ".jpg";
              el.style.display = "";
          }
          else
          {
              el.src = "";
              el.style.display = "none";
          }
  
      }
  }    
  &lt;/script&gt;
  </code></pre>
  
  <p><strong>HTML</strong></p>
  
  <pre><code>&lt;h2&gt;Choose method of shipping&lt;/h2&gt;
  &lt;form name="shipping_list"&gt;
      &lt;input type="checkbox" name="shipping1" onclick='check_value(this, 1, "4", "shipping")'/&gt; USPS Ground&lt;br /&gt;
      &lt;input type="checkbox" name="shipping2" onclick='check_value(this, 2, "4", "shipping")'/&gt; FedEx         
  &lt;/form&gt;
  
  &lt;img id="imgBox4" src="#" style="display:none"&gt;
  </code></pre>