日期时间转换处理

1.获取一周中的第一天

//获取一周中的第一天
function getFirstDay(day) {    
    var now = day;
    var nowTime = now.getTime();
    var day = (now.getDay() == "0" ? "7" :now.getDay() );
    var oneDayLong = 24 * 60 * 60 * 1000;
    var MondayTime = nowTime - (day - 1) * oneDayLong;
    var monday = new Date(MondayTime);
    return monday;
}

2.获取一周中的最后一天

//获取一周中的最后一天
function getLastDay(day) {
    var now = day;
    var nowTime = now.getTime();
    var day = (now.getDay() == "0" ? "7" : now.getDay());
    var oneDayLong = 24 * 60 * 60 * 1000;
    var SundayTime =  nowTime + (7-day)*oneDayLong ; 
    var sunday = new Date(SundayTime);
    return sunday;
}

3.格式化日期：yyyy-MM-dd ,参数是日期类型、参数是字符类型

//格式化日期：yyyy-MM-dd ,参数是日期类型
function formatDate(date) {
    var myyear = date.getFullYear();
    var mymonth = date.getMonth() + 1;
    var myweekday = date.getDate();

    if (mymonth < 10) {
        mymonth = "0" + mymonth;
    }
    if (myweekday < 10) {
        myweekday = "0" + myweekday;
    }
    return (myyear + "-" + mymonth + "-" + myweekday);
}

//获取日期，如2014-01-22，参数是字符类型
function getDateFun(d) {
    var tt = new Date(d.toString().replace(/\-/g, "/").replace(/\-/g, "/"));
    var date = tt.getFullYear() + "-";
    var mm = tt.getMonth() + 1;
    date += (mm >= 10 ? mm : "0" + mm) + "-";
    date += (tt.getDate() >= 10 ? tt.getDate() : "0" + tt.getDate());
    return date;
}

 

4.获取时间段，如08:00

//获取时间段，如08:00
function getTime(d) {
    var tt = new Date(d.toString().replace(/\-/g, "/").replace(/\-/g, "/"));
    var hour = (tt.getHours() >= 10 ? tt.getHours() : "0" + tt.getHours());
    var minute = (tt.getMinutes() >= 10 ? tt.getMinutes() : "0" + tt.getMinutes());
    var date = hour + ":" + minute;
    return date
}

5.获取每月天数

//获取每月天数
function DayNumOfMonth(date) {
    var tt = new Date(date.toString().replace(/\-/g, "/").replace(/\-/g, "/"));
    var d = new Date(tt.getFullYear(), tt.getMonth(), 1);
    d.setDate(d.getDate() + 32 - d.getDate());
    return (32 - d.getDate());
}

 6.和今天日期比较

 //格式化日期：yyyy-MM-dd ,参数是日期类型
    function formatDate(date) {
        var myyear = date.getFullYear();
        var mymonth = date.getMonth() + 1;
        var myweekday = date.getDate();

        if (mymonth < 10) {
            mymonth = "0" + mymonth;
        }
        if (myweekday < 10) {
            myweekday = "0" + myweekday;
        }
        return (myyear + "-" + mymonth + "-" + myweekday);
    }

        var tday = formatDate(new Date());
        var today = new Date(tday);
        var staffDay = "2020-03-20";
        var day = new Date(staffDay);
        if (!(today <= day)) {
            alert("输入日期小于今天")
            return;
        }