title: jQuery - How do I select an element by ID that has characters?
body: <p>I working with the following form on a WordPress website: </p>
  
  <pre><code>&lt;input id="abc_settings[update_date]" name= "abc_settings[update_date]" 
  type="checkbox" value="1" &lt;?php checked('1', $abc_options['update_date']); ?&gt;/&gt;
  </code></pre>
  
  <p>If I change the id to "update", I can select it using</p>
  
  <pre><code>value = $('#update').val();
  </code></pre>
  
  <p>However, I couldn't figure out how to get the value of <code>abc_settings[update_date]</code>. 
  This one is not working: </p>
  
  <pre><code>value = $('abc_settings[update_date]').val();
  </code></pre>
  
  <p>I keep the name abc_settings so that I can use <code>global $abc_settings</code> and <code>global $abc_options</code> in WordPress.</p>
  
  <p>Any help would be appreciated. </p>