Javascript：计算给定年份的月份天数 [英] Javascript: calculate number of days in month for a given year

问题描述

我有一个HTML页面，这个月份和日期都有3个下拉列表，我想知道是否有办法根据月份和年份正确填写月份下降。

I have a HTML page with 3 dropdowns for the month, day and year and I was wondering if there was a way to populate the month drop down properly depending on the month and year.

我以前没有在客户端这样做，但它看起来像很多控件，如jQuery DatePicker在幕后。

I haven't done this before on the client side, but it looks like a lot of controls like the jQuery DatePicker are doing that behind the scenes.

推荐答案

您可以使用日期对象：

var monthStart = new Date(year, month, 1);
var monthEnd = new Date(year, month + 1, 1);
var monthLength = (monthEnd - monthStart) / (1000 * 60 * 60 * 24)

使用 Date 对象的算术可以产生几毫秒。

Arithmetic with Date objects gives a number of milliseconds.

这甚至可以在十二月使用; Date构造函数通过围绕来处理超出范围的参数。

This will even work for December; the Date constructor handles out-of-range arguments by wrapping around.

请注意， month 是基于零（它必须介于 0 和 11 之间）

Note that month is zero-based (it must be between 0 and 11)

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