title: Regex that will match only if it starts with a pattern
body: <pre><code>/[\w-:/]+/g
  </code></pre>
  
  <p>This regex matches all alphanumeric &amp; underscore words (which may also contain characters like <code>-</code>, <code>:</code> and <code>/</code>).</p>
  
  <p>How to change this regex so that it matches only if the words begin with <code>**:</code>, where <code>*</code> is any alphanumeric character? Example: match <code>xs:qwerty:asd-zxc</code>, but not <code>qwerty:asd-zxc</code>.</p>