title: Negative lookbehind for all `{{` not preceded by `<em>`
body: <p>Given a string such as</p>
  
  <pre class="lang-none prettyprint-override"><code>The quick brown {{ fox }} jumped over the lazy &lt;em&gt;{{ dog }}&lt;/em&gt;
  </code></pre>
  
  <p>I'm looking for a pattern that will match all instances of <code>{{</code> <em>not</em> preceded by the <code>&lt;em&gt;</code> block</p>
  
  <p>Whilst the pattern <code>/(?&lt;!&gt;)\{{2}/gm</code> will work, this is not an option for Firefox and IE flavours of JS.</p>
  
  <p>I’ve done a fair bit of digging and can find a great deal of examples that almost get there but not quite. Getting a positive match for the string <code>_&gt;{{_</code> is no problem, but it’s the reverse of this that I’m looking for.</p>
  
  <p>I feel like I might be heading in the wrong direction with a lookup approach like this. Am I missing something more simple here?</p>