title: Find all groups of 9
body: <p>I am learning JS regex, so I am thinking about this example string <code>99s999s99s99</code>. 
  Now I want to find all number sequences within this string. I tried the following:</p>
  
  <pre><code>var s = /(\d+)/g;
  var a = '99s999s99s99';
  s.exec(a);
  
  var s = /(\d+)/;
  var a = '99s999s99s99';
  s.exec(a);
  </code></pre>
  
  <p>but both are producing the following output:
  <code>[ '99', '99', index: 0, input: '99s999s99s99' ]</code></p>
  
  <p>How to find all the groups of <code>9</code>s? </p>