title: Replacing string that does not include given pattern
body: <p>I'm looking to replace any character in the string that does not match the given pattern</p>
  <pre><code>300x300
  </code></pre>
  <p>If a string is something like the following:</p>
  <pre><code>blahblah300x300dingding
  </code></pre>
  <p>I would like to remove the following bolded text:</p>
  <p><strong>blahblah</strong>300x300<strong>dingding</strong></p>
  <p>So far i've created this regex expression, but so far it only removes the end characters that don't match, but i'd like it to match the beginning ones that dont match too.</p>
  <p>Here is my expression:</p>
  <pre><code>(?&lt;=(.*300x300)).+
  </code></pre>
  <p>I'd like to use <code>String.replace(REGEX, '')</code> to remove any value that does not match the pattern.</p>