问获取跳出办公时间的两个日期时间之间的时间差

EN

function officeTimeDiff(a, b) {
    a = moment(a);
    b = moment(b);
    if (b.diff(a) < 0) return 0;
    if (a.hour() <   9) a = a.hour(9).startOf('hour');
    if (a.hour() >= 18) a = a.add(1, 'day').hour(9).startOf('hour');    
    if (b.hour() <   9) b = b.add(-1, 'day').hour(18).startOf('hour');
    if (b.hour() >= 18) b = b.hour(18).startOf('hour');
    const diff = b.clone().year(a.year()).month(a.month()).date(a.date()).diff(a);
    a = a.startOf('day');
    b = b.startOf('day');
    return diff + moment.duration(b.diff(a, 'day') * 9, 'hour').asMilliseconds();
}

console.log(moment.utc(officeTimeDiff('2018-02-19 19:22:09', '2018-02-20 11:01:08')).format('HH:mm:ss'));

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