title: Regex: Contains string exact n times
body: <p>I need a regex that is true when a string contains a substring exact for example 2 times. So</p>
  
  <p><code>asdgsadg hello asdadsg hello dasadg</code> would be true</p>
  
  <p><code>asdgsadg hello asdadsg hello dasadg hello</code> would be false</p>
  
  <p>when the substring is <code>hello</code></p>
  
  <p>Unfortunately I can't do <code>/hello/g</code> and count the length...</p>
  
  <p>Thanks!</p>