关于Date的方法总结

1. 手动获取该日期所在的周中的周一日期和周日日期

function getWeekDays (inputDay:any) {
    const oneDayTime = 1000 * 60 * 60 * 24;
    const today = new Date(inputDay);
    // 若那一天是周末时，则强制赋值为7
    const todayDay = today.getDay() || 7;
    const startDate = new Date(
        today.getTime() - oneDayTime * (todayDay - 1)
    );
    const dateList = [];
    const start = new Date(startDate.getTime());
    const end = new Date(startDate.getTime() + 6 * oneDayTime);
    dateList.push(start);
    dateList.push(end);
    return dateList;
}

2. 为了显示需要，把一位数字转换成两位

function addZero (t: number) {
    return t < 10 ? '0' + t : t;
}

3. 将国际标准时间转换为yyyy-mm-dd格式

function changeDate (date:any) {
    const month = date.getMonth() + 1;
    const day = date.getDate();
    return date.getFullYear() + '-' + addZero(month) + '-' + addZero(day);
}

4. 将国际标准时间转换为 yyyy-mm-dd HH:MM 格式

function changeDate2Min (date:any) {
    const month = date.getMonth() + 1;
    const day = date.getDate();
    const hour = date.getHours();
    const min = date.getMinutes();
    return date.getFullYear() + '-' + addZero(month) + '-' + addZero(day) + ' ' + addZero(hour) + ':' + addZero(min);
}

5. 获取周一到周日的日期

function weekMonth(currentTime:any) {
    const currentDate = new Date(currentTime);
    const timesStamp = currentDate.getTime();
    const currenDay = currentDate.getDay();
    const dates = [];
    for (let i = 0; i < 7; i++) {
        const date = new Date(timesStamp + 24 * 60 * 60 * 1000 * (i - (currenDay + 6) % 7)).toLocaleDateString().replace(/\//g, '-');
        const dateList = date.split('-');
        Number(dateList[1]) >= 10 ? dateList[1] = '' + dateList[1] : dateList[1] = '0' + dateList[1];
        Number(dateList[2]) >= 10 ? dateList[2] = '' + dateList[2] : dateList[2] = '0' + dateList[2];
        const dataStr = dateList.join('-');
        dates.push(dataStr);
    }
    return dates;
}

6. 返回当前日的前某某天, days 想要往前推多少天,yyyy-MM-dd 格式的日期

function getDayBeforeYmd(days: number) :string {
    const curDate = new Date();
    const newDate = new Date(curDate.getFullYear(), curDate.getMonth(), curDate.getDate() - days);
    return changeDate(newDate);
}

7. 返回符合条件的星期日期

function getMonthWeek(year:any, month:any) {
    // 该月最后一天
    const lastDay = new Date(year, month, 0).getDate();
    // 该月有几周
    const weekNum = Math.ceil(lastDay / 7);
    return { weekNum, lastDay };
}

function getMondayTime(year:any, month:any, weekNum:any) {
    const date = new Date();
    // 该月第一天
    date.setFullYear(year, month - 1, 1);
    // 第一天是星期几
    let monthFirstWeek = date.getDay();
    // 如果等于0代表是周日
    if (monthFirstWeek === 0) monthFirstWeek = 7;
    // 第一个满足条件的日期
    let firstWeekDate;
    if (monthFirstWeek < weekNum) {
        firstWeekDate = weekNum - monthFirstWeek + 1;
    } else if (monthFirstWeek > weekNum) {
        firstWeekDate = 7 - monthFirstWeek + weekNum + 1;
    } else {
        firstWeekDate = 1;
    }
    return firstWeekDate;
}

function getTimeFunc(year:any, month:any, weekNum:any) {
    const weekObj = getMonthWeek(year, month);
    // 获得该月几周
    const weeks = weekObj.weekNum;
    const lastDay = weekObj.lastDay;
    // 获取月第一个想要拿到星期的日期
    const oneDate = getMondayTime(year, month, weekNum);
    const weeksAll = []; // 所有符合条件的星期
    for (let i = 0; i < weeks; i++) {
        const date = addZero(oneDate + i * 7);
        if (date <= lastDay) weeksAll.push(year + '-' + addZero(month) + '-' + date);
    }
    return weeksAll;
}