title: how can i divide numeric elements in an array while keeping the values of non-numeric ones
body: <p>given this array ['1', 23, null, 46.5, '34e2', , false, 'true', , 40], how can i divide the numeric elements in it by 10, but also keeping the non numeric elements in it, without modifying those values.
  what i did so far is this:</p>
  
  <pre><code>var divide = numbers.map(function(x){
      if(typeof x === 'number' &amp;&amp; isFinite(x)){
      return x / 10;
      }
  });
  
  console.log(divide); // [undefined, 2.3, undefined, 4.65, undefined, 6: undefined, 7: undefined, 9: 4]
  </code></pre>