修复小数计算精度不准确方法

Number.prototype.mul = function (arg) {
        var m = 0, s1 = this.toString(), s2 = arg.toString();
        try {
            m += s1.split('.')[1].length
        } catch (e) {
        }
        try {
            m += s2.split('.')[1].length // m是累加结果
        } catch (e) {
        }
        return Number(s1.replace('.', '')) * Number(s2.replace('.', '')) / Math.pow(10, m) // 直接去掉小数点，转为整型计算，最后缩小n倍
    };

function louis(arg){
    var m=0, s1 = arg.toString();
    try {
      m = s1.split('.')[1].length; 
    } catch (e) {
    }
    return Number(s1.replace('.',''))/Math.pow(10,m-2)
};