题解 | #分隔符#

function _comma(number) {
    // 补全代码
    const numStr = String(number)
    const numArr = numStr.split('')
    if (number < 0) {
        numArr.shift()
    }
    const resArr = []
    let count = 0
    for (let i = numArr.length - 1; i >= 0 ; i--) {
        resArr.unshift(numArr[i])
        count++
        if (count % 3 === 0 && count !== numArr.length) {
            resArr.unshift(',')
        }
    }
    if (number < 0) {
        resArr.unshift('-')
    }
    return resArr.join('')
}