js怎么向上取整保留两位

Question

Math.ceil(6.008) => 6 怎么取整为 6.01

Answer 1

function ceil(num, byte){
    let n = Math.pow(10, byte)
    return Math.ceil(num * n) / n
}

ceil(6.008, 2) //6.01

Answer 2

没太明白你这个“向上取整”是指“进一法”？因为你给这个例子用“四舍六入五看双”或“四舍五入”也是成立的。

就先根据字面意思理解当作是“进一法”吧：

Number.prototype.toCeil = function (num = 0) {
    if (!(num >= 0 && num <= 100)) {
        throw new RangeError('toCeil() digits argument must be between 0 and 100.');
    }

    let val = Math.ceil(this * Math.pow(10, num)) / Math.pow(10, num) + '';
    if (num > 0) {
        const intp = val.split('.')[0],
            decp = val.split('.')[1] || '';
        if (decp.length < num) {
            val = intp + '.' + decp.padEnd(num, '0');
        }
    }

    return val;
}


let num1 = 6.008;
let str2 = num.toCeil(2);
console.log(str1); //6.01

let num1 = 6.001;
let str2 = num.toCeil(2);
console.log(str2); //6.01