title: How to determine which options selected in multiple <select>?
body: <p>I have this <code>&lt;select&gt;</code>:</p>
  
  <pre><code> &lt;select id="week" multiple="multiple" &gt;
      &lt;option value="1"&gt;Monday&lt;/option&gt;
      &lt;option value="2"&gt;Tuesday&lt;/option&gt;
      &lt;option value="3"&gt;Wednesday&lt;/option&gt;
      &lt;option value="4"&gt;Thursday&lt;/option&gt;
      &lt;option value="5"&gt;Friday&lt;/option&gt;
      &lt;option value="6"&gt;Saturday&lt;/option&gt;
      &lt;option value="7"&gt;Sunday&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>How can I know that whether each <code>&lt;option&gt;</code> is selected or not in jQuery or JS?</p>