title: check if any duplicate words exist in a string using regex
body: <p>Using regex in javascript, how to check for the condition when duplicate words are present in a string?
  The words could be located any where in the string:</p>
  
  <p>Given: "but boys run fast boys are strong" or<br>
  "boys boys"</p>
  
  <p>expected result: true, since there are 2 repeats of the word "boys"</p>