title: remove all dups and negative numbers from 3 arrays
body: <p>I recently had a technical job interview. the code challenge i was asked to solve was given 3 arrays of numbers. goal was to remove all dups and negative nums
  i was able to remove dups but not duplicates, so far i have the following code. what am i missing?</p>
  
  <pre><code>let array1=[10, 200, 10, 200, 100, 100, 200, 200, 200, 200, -99, -6, 0, -859]
  let array2 = [100, 200, 100, 200, 689, 689, 200, 400, 210, 200, -58, 200, -305, -6, 0, -859]
  let array3 =[100, 200, 100, 200, 689, 689, 200, 400, 210, 400, -6, 200, -305, -6, 0, -859]
  
  const arrays = {
      array1,array2,array3
  }
  
  
  let nodups=Array.from(new Set(array1.concat(array2,array3)))
  console.log(nodups);
  </code></pre>