js根据指定顺序排序

        Array.prototype.csSort = function() {
            var newarr = this;
            let order = [6,5,4,3,2,1,8,7]
              let tableData=newarr;
              tableData = newarr.sort((a,b) => {
                return order.indexOf(a) - order.indexOf(b)
              })
            return newarr;
        }

var myarray_group = [1,2,3,8]

myarray_group.csSort()