JavaScript：如何获取上个月（本周）的7天前的日期

Question

我正在构建一个函数，该函数将根据用户作为参数发送给它的内容动态生成日期。 我需要为上周，本周，上个月，本月，过去7天，过去30天之类的案件创建日期。 由于我要向数据库发送日期和日期，因此需要像yyyy-mm-dd那样格式化它们。 我的问题是如何获取上周末和上周初（本周开始）的日期，以及如何针对从当前日期中减去7或30的情况更正日期。

到目前为止，这是我的代码，但仅适用于当月的日期：

function myDate(day){
    var date = new Date();
    var dd = date.getDate() - day;
    var mm = date.getMonth()+1; //January is 0!
    var yyyy = date.getFullYear();
    if(dd<10){
        dd='0'+dd
    }
    if(mm<10){
        mm='0'+mm
    }
    var newDate = yyyy+'-'+mm+'-'+dd;

    return newDate;
}

var today = myDate(0);
var yesterday = myDate(1);
var sevenDaysAgo = myDate(7);
var thirtyDaysAgo = myDate(30);

更新的代码：

如果有人需要，这就是我使用moment.js做到的：

var date = moment().format("YYYY-MM-DD");
var yesterday = moment().subtract(1, 'day').format('YYYY-MM-DD');
var sevenDaysAgo = moment().subtract(7, 'day').format('YYYY-MM-DD');
var thirtyDaysAgo = moment().subtract(30, 'day').format('YYYY-MM-DD');
var lastWeekStart = moment(date).weekday(-6).format('YYYY-MM-DD');
var lastWeekEnd = moment(date).weekday(1).format('YYYY-MM-DD');
var thisWeekStart = moment(date).weekday(1).format('YYYY-MM-DD');
var startOfMonth = moment().startOf('month').format('YYYY-MM-DD');
var startOfLastMonth = moment().subtract(1, 'month').startOf('month').format('YYYY-MM-DD');
var endOfLastMonth = moment().subtract(1, 'month').endOf('month').format('YYYY-MM-DD');

Answer 1

DIY Date处理

对于好奇或厌恶库的人，以下示例显示了如何在Vanilla JavaScript中创建自己的函数，这些函数可以为您执行这些计算：

 /* Define new prototype methods on Date object. */ // Returns Date as a String in YYYY-MM-DD format. Date.prototype.toISODateString = function () { return this.toISOString().substr(0,10); }; // Returns new Date object offset `n` days from current Date object. Date.prototype.toDateFromDays = function (n) { n = parseInt(n) || 0; var newDate = new Date(this.getTime()); newDate.setDate(this.getDate() + n); return newDate; }; // Returns new Date object from start of week of current Date object // optionally offset `n` weeks from week of current Date object. Date.prototype.toStartOfWeek = function (n) { var newDate = new Date(this.getTime()); newDate.setDate(this.getDate() - this.getDay()); return n ? newDate.toDateFromDays(n * 7) : newDate; }; // Returns new Date object from start of month of current Date object // optionally offset `n` months from month of current Date object. Date.prototype.toStartOfMonth = function (n) { n = parseInt(n) || 0; var newDate = new Date(this.getTime()); newDate.setMonth(this.getMonth() + n, 1); return newDate; }; /* Instantiate a Date. */ var today = new Date(); /* Chain all the things. */ console.log( 'Today: ', today.toISODateString() ); console.log( '7 days ago: ', today.toDateFromDays(-7) .toISODateString() ); console.log( '30 days ago: ', today.toDateFromDays(-30) .toISODateString() ); console.log( '90 days from now: ', today.toDateFromDays(90) .toISODateString() ); console.log( 'Start of this week: ', today.toStartOfWeek() .toISODateString() ); console.log( 'End of this week: ', today.toStartOfWeek(1) .toDateFromDays(-1) .toISODateString() ); console.log( 'Start of last week: ', today.toStartOfWeek(-1) .toISODateString() ); console.log( 'End of last week: ', today.toStartOfWeek() .toDateFromDays(-1) .toISODateString() ); console.log( 'Start of next week: ', today.toStartOfWeek(1) .toISODateString() ); console.log( 'End of next week: ', today.toStartOfWeek(2) .toDateFromDays(-1) .toISODateString() ); console.log( 'Start of this month: ', today.toStartOfMonth() .toISODateString() ); console.log( 'End of this month: ', today.toStartOfMonth(1) .toDateFromDays(-1) .toISODateString() ); console.log( 'Start of last month: ', today.toStartOfMonth(-1) .toISODateString() ); console.log( 'End of last month: ', today.toStartOfMonth() .toDateFromDays(-1) .toISODateString() ); console.log( 'Start of next month: ', today.toStartOfMonth(1) .toISODateString() ); console.log( 'End of next month: ', today.toStartOfMonth(2) .toDateFromDays(-1) .toISODateString() ); 

有关此示例中使用的本机方法的更多信息，请参见Date构造函数的MDN文档 。

Answer 2

实际上，我没有收到该错误，但是如果我需要按照提供的问题对日期进行预格式化，则不会。

 var startOfWeek = moment().day(1).format(); // day(0) if in your country start of week is on Sunday
 var final = moment(startOfWeek).format('YYYY-MM-DD');