D3 Examples - questions again

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<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>
​
<body>
  <script>
   
    //define a function weirdArraySort(a)
    function weirdArraySort(a){
      //a is an array of mixed numbers and latters
    
     numbers = []
     strings = []
      
      a.forEach(function(b){
        if(typeof b === "string"){
          strings.push(b)
        }
        else if (typeof b === "number"){
          numbers.push(b)
        }
      })
      numbers.sort()
      strings.sort()
      strings.reverse()
      result=strings.concat(numbers)
      //return an array
      return result;
    }
    console.log(weirdArraySort(["A", 3, "X", 1, "Q"]))
    
  </script>
</body>
​
    