title: Return highest and lowest number in a string of numbers with spaces
body: <p>Let's say I have a string of numbers separated by spaces and I want to return the highest and lowest number. How could that best be done in JS using a function? Example: </p>
  
  <pre><code>highestAndLowest("1 2 3 4 5"); // return "5 1"
  </code></pre>
  
  <p>I would like the both numbers to be  returned in a string. The lowest number first followed by a space then the highest number.</p>
  
  <p>Here is what I have so far:</p>
  
  <pre><code>function myFunction(str) {
      var tst = str.split(" ");
      return tst.max();
  }
  </code></pre>