js精度减法函数

 iSub(arg1, arg2) { // 减法
                let r1, r2, m, n
                try {
                    r1 = arg1.toString().split(‘.‘)[1].length
                } catch (e) {
                    r1 = 0
                }
                try {
                    r2 = arg2.toString().split(‘.‘)[1].length
                } catch (e) {
                    r2 = 0
                }
                m = Math.pow(10, Math.max(r1, r2))
                n = (r1 >= r2) ? r1 : r2
                return ((arg1 * m - arg2 * m) / m).toFixed(n)
            },