<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <script type="text/javascript">
    var num = 4;//每个子数组里的元素个数
    var arr = [1,4,5,6,34,34,67,895,2456,87,9,5,23,884,56];
    var Arr = new Array(Math.ceil(arr.length/num));
    for(var i = 0; i<Arr.length;i++){
    Arr[i] = new Array();
    for(var j = 0; j<num; j++){
    Arr[i][j] = '';
    }
    }
    for(var i = 0; i<arr.length;i++){
    Arr[parseInt(i/num)][i%num] = arr[i]; 
    } 
    console.log(Arr)
    </script>
  </head>
  <body>
  </body>
</html>