title: HTML5 localStorage replace data to already existing key
body: <p>I have the following <a href="http://dev.w3.org/html5/webstorage/" rel="noreferrer">localStorage</a> key:</p>
  
  <pre><code>localStorage.setItem(1, "&lt;div id='MyId'&gt;value 1&lt;/div&gt;&lt;div id='NewId'&gt;other value&lt;/div&gt;");
  </code></pre>
  
  <p>Is it possible to replace, change only the second id, make the:</p>
  
  <pre><code>&lt;div id='MyId'&gt;value 1&lt;/div&gt;&lt;div id='NewId'&gt;other value&lt;/div&gt;
  </code></pre>
  
  <p>turn into</p>
  
  <pre><code>&lt;div id='MyId'&gt;value 1&lt;/div&gt;&lt;div id='NewId'&gt;replaced value&lt;/div&gt;
  </code></pre>
  
  <p>I do not want to delete this key and create a new one, just replace a part of it.
  Thank you.</p>