当传递给“新日期"时，javascript 中 yyyy-mm-dd 和 yyyy/mm/dd 的结果不同

问题描述

我在 nodejs repl 下执行下面的语句，我在同一日期得到了两个不同的结果

I was executing below statement under nodejs repl and i was getting two different result for same date

var dateStr1 = "2015/03/31";
var dateStr2 = "2015-03-31";
var date1 = new Date(dateStr1);//gives Tue Mar 31 2015 00:00:00 GMT+0530 (IST)
var date2 = new Date(dateStr2);//gives Tue Mar 31 2015 05:30:00 GMT+0530 (IST)

在第一个小时，分钟，秒全为零，而在第二个小时，分钟默认设置为时区小时，分钟，即 5:30

In the 1st one hour,min,seconds are all zeros while in the 2nd one by default hour,min is getting set to as a timezone hour,min which is 5:30

推荐答案

归结为 Date.parse() 如何处理 ISO-8601 日期格式.

It boils down to how Date.parse() handles the ISO-8601 date format.

日期时间字符串可能是 ISO 8601 格式.例如，可以传递和解析2011-10-10"(只是日期)或2011-10-10T14:48:00"(日期和时间).UTC 时区用于解释不包含时区信息的 ISO 8601 格式的参数(请注意，ECMAScript ed 6 草案指定将不带时区的日期时间字符串视为本地时间，而不是 UTC)

The date time string may be in ISO 8601 format. For example, "2011-10-10" (just date) or "2011-10-10T14:48:00" (date and time) can be passed and parsed. The UTC time zone is used to interpret arguments in ISO 8601 format that do not contain time zone information (note that ECMAScript ed 6 draft specifies that date time strings without a time zone are to be treated as local, not UTC)

您的第一个日期格式 2015/03/31 是 假设为 2015 年 3 月 31 日凌晨 12 点您当前的时区.
您的第二个日期格式 2015-03-31 被视为 ISO-8601，并假定为 2015 年 3 月 31 日凌晨 12 点UTC 时区.

Your first date format 2015/03/31 is assumed to be March 31st, 2015 at 12am in your current time zone.
Your second date format 2015-03-31 is seen as ISO-8601 and is assumed to be March 31st, 2015 at 12am UTC time zone.

链接文档中的假定时区差异"标题更详细:

The "Differences in assumed time zone" heading from the linked documentation goes into a bit more detail:

给定日期字符串2014 年 3 月 7 日"，parse() 假定为本地时区，但给定 ISO 格式，例如2014-03-07"，它将假定时区为 UTC.因此，使用这些字符串生成的 Date 对象将代表不同的时间点，除非系统设置为 UTC 的本地时区.这意味着看起来相同的两个日期字符串可能会产生两个不同的值，具体取决于要转换的字符串的格式(此行为在 ECMAScript ed 6 中进行了更改，因此两者都将被视为本地).

Given a date string of "March 7, 2014", parse() assumes a local time zone, but given an ISO format such as "2014-03-07" it will assume a time zone of UTC. Therefore Date objects produced using those strings will represent different moments in time unless the system is set with a local time zone of UTC. This means that two date strings that appear equivalent may result in two different values depending on the format of the string that is being converted (this behavior is changed in ECMAScript ed 6 so that both will be treated as local).

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