JS两个小数相加，精度不对问题

扩大小数点位数最多的倍数

        var num1 = 1.528;num2 = 1.2;
        var r1, r2, m;
        try {
            r1 = num1.toString().split('.')[1].length;
        } catch (e) {
            r1 = 0;
        }
        try {
            r2 = num2.toString().split(".")[1].length;
        } catch (e) {
            r2 = 0;
        }
        m = Math.pow(10, Math.max(r1, r2));
        a = Math.round(num1 * m + num2 * m) / m
        console.log(a);