title: Using JavaScript to dynamically create HTML on page load
body: <p>Here is a very brief background of what I want to do. I need to create a very small block of JavaScript that will be given to many websites to embed in their home pages. Then, when visitors hit those home pages, a URL will automatically get called that collects certain statistics and returns a small image. I have some of this in place already as follows:</p>
  
  <pre><code>        &lt;script&gt;
              /* Determine if there is a cookie already exists and get its value if not. */
              var userId;
              match = document.cookie.match(new RegExp("someUserId" + '=([^;]+)'));
              if (match)
                  userId = match[1];
              else {
                  /* generate a random 10 character string */
                  userId = (Math.random() + 1).toString(36).substring(5, 15);
  
                  /* Store this as a cookie value */
                  &lt;needs to be done&gt;
              }
  
              /* This is what I need help with. A page is called when the home page loads to collect some stats and return a small image */
              &lt;a href="http://www.SomeAnalysisSite.com/"&gt;&lt;img src="http://www.SomeAnalysisSite.com/Log/?Id=1@userId=xxx" alt=""/&gt;&lt;/a&gt;
          &lt;/script&gt;
  </code></pre>
  
  <p>The piece I don't know how to do is the very last line (with the img tag). I need to generate this dynamically and inserted into the DOM (I think), after the value of "userId" is generated so it can be included as a query parameter in the img src URL. Or perhaps there is a better way? Of course, I'll minify this before it's sent to third party websites.</p>