title: Javascript regexp creation error
body: <p>I have the following JavaScript code:</p>
  
  <pre><code>aw_check_custom_validation['my-phone'] = /^\+[0-9]{1,3}(\s[0-9]{1,6}\s|\([0-9]{1,6}\)|[0-9]{1,6})[0-9\s]{5,8}$/u;
  </code></pre>
  
  <p>and I receive the following error:</p>
  
  <pre><code>Uncaught SyntaxError: Invalid flags supplied to RegExp constructor 'u'
  </code></pre>
  
  <p>Why the /u flag causes this error?</p>