javascript 如何从周数和年份中获取一周的第一个日期和最后一个日期？
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How to get first date and last date of the week from week number and year?
提问by balaphp
In JavaScript I want to get first date of the week and last date of the week by week number and year only.
在 JavaScript 中，我只想按周数和年份获取一周的第一个日期和一周的最后一个日期。
For example if I my input is:
例如，如果我的输入是：
2(week),2012
2(week),2012
Then my output should be:
那么我的输出应该是：
2012-01-08 and 2012-01-14
2012-01-08 and 2012-01-14
采纳答案by bardiir
Try this:
试试这个：
var year = 2012;
var week = 2;
var d = new Date("Jan 01, " + year + " 01:00:00");
var w = d.getTime() + 604800000 * (week - 1);
var n1 = new Date(w);
var n2 = new Date(w + 518400000)
console.log(n1);
console.log(n2);n1 contains the first day of the week
n2 contains the last day of the week
n1 包含一周的第一天
n2 包含一周的最后一天
As for the constants:
604800000 is one week in milliseconds
518400000 is six days
至于常数：
604800000 是以毫秒为单位的一周
518400000 是六天
回答by Xig480
A little change to @bardiir 's answer, if the first day of the year is not Sunday(or Monday) that result is not correct. You should minus the number of the first day.
对@bardiir 的回答稍作改动，如果一年中的第一天不是星期日（或星期一），则结果不正确。你应该减去第一天的数量。
Changed code
更改代码
firstDay = new Date(2015, 0, 1).getDay();
console.log(firstDay);
var year = 2015;
var week = 67;
var d = new Date("Jan 01, " + year + " 01:00:00");
var w = d.getTime() - (3600000 * 24 * (firstDay - 1)) + 604800000 * (week - 1)
var n1 = new Date(w);
var n2 = new Date(w + 518400000)
console.log(n1);
console.log(n2);if you wish the first is Sunday, change the (firstDay-1) to
如果您希望第一个是星期日，请将 (firstDay-1) 更改为
回答by Chandresh M
you can check and try with below link.
您可以使用以下链接检查并尝试。
How to get first and last day of the week in JavaScript
It will may helpful to you.
它可能对你有帮助。
Thanks.
谢谢。
回答by perumalsamy
dt = new Date();
var firstDateOfWeek=(dt.setDate(dt.getDate()-dt.getDay()));
var lastDateOfWeek=(dt.setDate(dt.getDate()+6-dt.getDay()));
