1,将数组array分成长度为subGroupLength的小数组并返回新数组

function group(array, subGroupLength) {

      let index = 0;

      let newArray = [];

      while(index < array.length) {

          newArray.push(array.slice(index, index += subGroupLength));

      }

      return newArray;

  }
 2,例如：

 var Array = [1,2,3,4,5,6,7,8,9,10,11,12];;

 var groupedArray = group(Array, 6);
 得到的groupedArray 数组为：
    groupedArray[[1,2,3,4,5,6],[7,8,9,10,11,12]]