title: Checking number of strings inside array that can be successfully converted into a number
body: <p>Here's a description of the task I'm working on:</p>
  
  <p>Write a function called countNumbers, which accepts an array of strings. The function should return a count of the number of strings in the array that can be successfully converted into a number. For example, the string "1" can be successfully converted to the number 1, but the string "hello" cannot be converted into a number.</p>
  
  <pre><code>countNumbers(['a','b','3','awesome','4']); // 2
  countNumbers(['32', '55', 'awesome', 'test', '100']); // 3
  countNumbers([]); // 0
  countNumbers(['4','1','0','NaN']); // 3
  countNumbers(['7', '12', 'a', '', '6', '8', ' ']); // 4
  </code></pre>
  
  <p>My code:</p>
  
  <pre><code>function countNumbers(arr) {
      var count = 0;
      for (num in arr) {
          if (Number(arr[num]) !== NaN) {
              count++;
          }
      }
      return count;
  }
  </code></pre>
  
  <p>When I console log (Number(arr[num]), I do see NaN in the console, however when I'm comparing in the loop, the count variable does not increase and I end up with a return value equal to the length of the array.</p>
  
  <p>Any tips on what I could be doing wrong or what I overlooked are much appreciated.</p>