title: Month selection dropdown in HTML and JavaScript
body: <p>I have 2 drop downs in HTML both representing months. So I want a validation like following. </p>
  
  <p>If I select the first drop down month as April, then the next drop-down menu should start from the month April. If the first one is changed to June then the second should change to June.</p>
  
  <pre><code>&lt;div id="head2" style="width:15%;float:right;margin-left:5px;"&gt;
      &lt;select id='gMonth2' onchange="show_month()"&gt;
      &lt;option value=''&gt;--Select Month--&lt;/option&gt;
      &lt;option selected value='1'&gt;Janaury&lt;/option&gt;
      &lt;option value='2'&gt;February&lt;/option&gt;
      &lt;option value='3'&gt;March&lt;/option&gt;
      &lt;option value='4'&gt;April&lt;/option&gt;
      &lt;option value='5'&gt;May&lt;/option&gt;
      &lt;option value='6'&gt;June&lt;/option&gt;
      &lt;option value='7'&gt;July&lt;/option&gt;
      &lt;option value='8'&gt;August&lt;/option&gt;
      &lt;option value='9'&gt;September&lt;/option&gt;
      &lt;option value='10'&gt;October&lt;/option&gt;
      &lt;option value='11'&gt;November&lt;/option&gt;
      &lt;option value='12'&gt;December&lt;/option&gt;
      &lt;/select&gt; 
      &lt;/div&gt;
  
  &lt;div id="head1" style="width:15%;float:right;margin-left:5px;"&gt;
          &lt;select id='gMonth1'&gt;
      &lt;option value=''&gt;--Select Month--&lt;/option&gt;
      &lt;option selected value='1'&gt;Janaury&lt;/option&gt;
      &lt;option value='2'&gt;February&lt;/option&gt;
      &lt;option value='3'&gt;March&lt;/option&gt;
      &lt;option value='4'&gt;April&lt;/option&gt;
      &lt;option value='5'&gt;May&lt;/option&gt;
      &lt;option value='6'&gt;June&lt;/option&gt;
      &lt;option value='7'&gt;July&lt;/option&gt;
      &lt;option value='8'&gt;August&lt;/option&gt;
      &lt;option value='9'&gt;September&lt;/option&gt;
      &lt;option value='10'&gt;October&lt;/option&gt;
      &lt;option value='11'&gt;November&lt;/option&gt;
      &lt;option value='12'&gt;December&lt;/option&gt;
      &lt;/select&gt; 
      &lt;/div&gt; 
  </code></pre>
  
  <p>The function will be:</p>
  
  <pre><code>function show_month()
  {
  //
  }
  </code></pre>
  
  <p>How should I write that function?</p>