title: Regex mask last 4 numbers
body: <pre><code>R.replace(/[0-9](?!([0-9]{4}))/g,'*','123456789'); 
  yields 12345****
  
  want to input 123-45-6789 and yield 123-45-****
  
  Currently based on above it yields ***-**-**** 
  </code></pre>
  
  <p>No idea why. I am using rambda js to simulate.
  <a href="http://ramdajs.com/docs/#replace" rel="nofollow noreferrer">http://ramdajs.com/docs/#replace</a></p>
  
  <p>need help to construct the regex for that . Any help is appreciated</p>