7>时间方法

new Date() 日期对象

let currentime = new Date()    // 返回中国标准时间
let year = currentime.getFullYear()  // 返回年 2022
let month = currentime.getMonth() + 1  // 返回月 6
let day = currentime.getDate()     // 返回日 21

以下封装用到的补0

// 一位数前补0
const correction = (time)=>{
    return time>=0 && time<10 ? '0'+time :time
}

获取今天的时间

// 获取今天的时间
export const getTodayTime =()=>{
    let currentime = new Date()
    let year = currentime.getFullYear()
    let month = currentime.getMonth() + 1
    let day = currentime.getDate()
    return correction(year) + '-' + correction(month) + '-' + correction(day)
}

获取最近7天的时间

// 获取最近7天的时间 
export const getSevenDays =()=>{

    let time = {
        one : getOneDay(0),
        two : getOneDay(-1),
        three : getOneDay(-2),
        four : getOneDay(-3),
        five : getOneDay(-4),
        six : getOneDay(-5),
        seven : getOneDay(-6),
    }
    return time
}

// 测试获取最近7天的日期
const getOneDay = (day)=>{
    let today = new Date();
    let targetday_milliseconds=today.getTime() + 1000*60*60*24*day;
    today.setTime(targetday_milliseconds); //注意，这行是关键代码
    let tYear = today.getFullYear();
    let tMonth = today.getMonth();
    let tDate = today.getDate();
    tMonth = correction(tMonth + 1);
    tDate = correction(tDate);
    return tYear+"-"+tMonth+"-"+tDate;
}

获取当前月份的所有日期

// 获取当前月份的所有日期
export const getMonthDays =()=>{
    let year = new Date().getFullYear()
    let month = new Date().getMonth() + 1
    let day = new Date(year, month, 0).getDate()
    let current_month_num = day
    let current_month = []
    for(let i = 1;i <= current_month_num;i++){
        let cday = month + '-' + i
        current_month.push(cday)
    }
    return current_month
}

获取今天和昨天的时间

// 获取今天和昨天的时间
export const getTodayYesTime =()=>{
    let currentime = new Date()
    let year = currentime.getFullYear()
    let month = currentime.getMonth() + 1
    let day = currentime.getDate()
    // console.log(year,month,day);
    let yesterday = new Date(today)
    let yesyear = yesterday.getFullYear()
    let yesmonth = yesterday.getMonth() + 1
    let yesday = yesterday.getDate() 
    let time = {
        today : correction(year) + '-' + correction(month) + '-' + correction(day),
        yesterday : correction(yesyear) + '-' + correction(yesmonth) + '-' + correction(yesday)
    }
    return time
}

// 获取上个月最后一天的日期

// 获取上个月最后一天的日期
export const lastMonth =()=>{
    let date = new Date()
    let year = date.getFullYear()
    let mon = date.getMonth() 
    if(mon == 0){
        mon = 12
        year = year - 1
    }
    let lastDay = new Date(year, mon, 0).getDate()
    return year + "-" + correction(mon) + "-" +lastDay
}

// 获取当前时间是本年的第几周

getWeek(val){
    console.log(val);
    let firstDay = new Date(val.getFullYear(), 0, 1)  // 当前年份的第一天
    let dayOfWeek = firstDay.getDay()  // 当前年份的第一天是周几
    let spendDay = 1
    if(dayOfWeek !=0){
        spendDay = 7 -dayOfWeek + 1  // 距离下周还有几天
    }

    firstDay = new Date(val.getFullYear(), 0, 1 + spendDay) //今年的第一周的第一天的日期

    let d = Math.ceil((val.valueOf() - firstDay.valueOf()) / 86400000) // 计算相差几天

    let result = Math.ceil(d / 7)
    let year = val.getFullYear()
    let week = result 
    if(dayOfWeek !== 0){
        week = result + 1
    }
    if(week === 53 && val.getDate() !== 26){
        week = 1
        year += 1
    }
    return `${year}年第${week}周`
}