问题
I am creating an app that will automatically update sitemap.xml each time new content is added to, or updated on the site.
According to Google's best practices the <lastmod></lastmod> tag should be formatted as follows:
<lastmod>2011-06-27T19:34:00+01:00</lastmod>
My question concerns the time formatting itself. I understand the 2011-06-27T19:34:00 part. What I do not understand is the +01:00, which I am assuming is the +/- UTC.
Is this a correct assumption?
My Time Zone Table looks like this:
So if the site was based in #4 Afghanistan the correct time would be:
2011-06-27T19:34:00+04:00
And if the site was based in #6 Alaska Standard Time the correct time would be: 2011-06-27T19:34:00-09:00
Is my assumption correct or am I not correctly understanding the +01:00?
回答1:
The lastmod tag is optional in sitmaps and in most of the cases it's ignored by search engines, because webmasters are doing a horrible job keeping it accurate. In any case, you may use it, and the format depends on your capabilities and requirements; you don't actually have to provide a timezone offset if you can't or don't want to, you can choose to go with a simple YYYY-MM-DD as well.
From the Lastmod definition section of sitemaps.org:
The date of last modification of the file. This date should be in W3C Datetime format. This format allows you to omit the time portion, if desired, and use YYYY-MM-DD.
If you want to go down to that granularity and provide the timezone offset as well, you're correct, it's UTC +/-. From W3C Datetime:
Times are expressed in local time, together with a time zone offset in hours and minutes. A time zone offset of "+hh:mm" indicates that the date/time uses a local time zone which is "hh" hours and "mm" minutes ahead of UTC. A time zone offset of "-hh:mm" indicates that the date/time uses a local time zone which is "hh" hours and "mm" minutes behind UTC.
And example, still from W3C:
1994-11-05T08:15:30-05:00 corresponds to November 5, 1994, 8:15:30 am, US Eastern Standard Time.
回答2:
Properly format last modified (lastmod) time for XML sitemaps in C#
var ss = DateTime.Now.ToString("yyyy-mm-ddThh:mm:ss:zzz");
回答3:
In PHP, you can use :
$lastmod = date("Y-m-d\Th:m:s+00:00");
This will display something like:
2018-02-14T08:02:28+00:00
回答4:
PHP should actually be:
date('Y-m-d\TH:i:s+00:00');
回答5:
The format for the lastmod field in Google Sitemaps XML for C# is the following:
var lastmod = DateTime.Now.ToString("yyyy-MM-ddTHH:mm:sszzz");
It provides values such as <lastmod>2018-08-24T09:18:38-04:00</lastmod> which is the W3C Datetime format.
回答6:
Date.prototype.toISOString()
The toISOString() method returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long (YYYY-MM-DDTHH:mm:ss.sssZ or ±YYYYYY-MM-DDTHH:mm:ss.sssZ, respectively). The timezone is always zero UTC offset, as denoted by the suffix "Z".
// expected output: 2011-10-05T14:48:00.000Z
来源：https://stackoverflow.com/questions/31349345/how-to-properly-format-last-modified-lastmod-time-for-xml-sitemaps