title: Regex created with constructor not working with Safari
body: <p>It is documented that one can create regex expressions using 2 methods: </p>
  
  <p>1.simple expression</p>
  
  <pre><code>   /ab+c/i;
  </code></pre>
  
  <p>2.using a constructor</p>
  
  <pre><code>  new RegExp(/ab+c/, 'i');
    new RegExp('ab+c', 'i');
  </code></pre>
  
  <p>I have used the version RegExp(/ab+c/, 'i') which passed in Chrome, Mozilla but not in Safari, returning an error:</p>
  
  <pre><code>cannot supply flags when constructing one regexp from another
  </code></pre>
  
  <p>I have switched to the first method and it works now but there are 2 things that are not clear for me:</p>
  
  <ol>
  <li><p>what does '/' character stand for in an expression like that. I've seen it added by default in online regex test sites </p></li>
  <li><p>why safari failed to work with the version that i used</p></li>
  </ol>