题解 | #分隔符#

function _comma(number) {
    let symbol = ''
    if(number < 0) {
        symbol = '-'
        number = Math.abs(number)
    }
    let arr = parseInt(number).toString().split("").reverse()
    let num = []
    let count = 0
    for(let i=0 ; i<arr.length ; i++) {
        if(count === 3 ) {
            num.push(',')
            count = 0
        }
        num.push(arr[i])
        count ++
    }
    return symbol + num.reverse().join('')
}