将数字 12345678 转化成 RMB 形式 如： 12,345,678

<script>
    let str = '1234132131232135678'
    let tmp = [...str].reverse()
    tmp = tmp
        .map((it, ind) =>
            ind % 3 === 0 ?
            [tmp[ind], tmp[ind + 1], tmp[ind + 2]]
            .reverse()
            .filter((it) => it !== undefined)
            .join('') :
            undefined
        )
        .filter((it) => it !== undefined)
        .reverse()
        .join(',')

    console.log(tmp)
</script>