title: How can a Firefox extension get its own version number programmatically?
body: <p><strong>How do I programatically get my own Firefox extension's version number with Javascript?</strong></p>
  
  <p>My extension has an install.rdf file containing the version number similar to below. I want to extract the contents of the <code>&lt;em:version&gt;</code> tag.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
   xmlns:em="http://www.mozilla.org/2004/em-rdf#"&gt;
    &lt;Description about="urn:mozilla:install-manifest"&gt;
      ...
      &lt;em:version&gt;1.0&lt;/em:version&gt;
      ...
    &lt;/Description&gt;
  &lt;/RDF&gt;
  </code></pre>