题解 | #分隔符#

    if(number < 0) {
        negative = '-'
        number = Math.abs(number);
    }
    number=number.toString();
    let sign = 0
    let sum =""
    for(let i=number.length-1 ; i>=0 ; i--) {
        if(sign === 3) {
            sum+=","
            sign = 0
        }
        sum+=number[i]
        sign ++
    }
    return negative+sum.split("").reverse().join("")