fix(sitemap): use post.lastUpdated

* post.updated = execution time of 'hexo generate'
* use moment.format() instead of Date.toISOString() to avoid timezone conversion
  - Use '[T00:00:00.000Z]' to ignore time, instead of '[T]HH:mm:ss.sss[Z]'
  - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString

themes/typing/scripts/sitemap/.sitemap.xml

@@ -3,10 +3,10 @@
   {% for post in posts %}
   <url>
     <loc>{{ post.permalink | uriencode }}</loc>
-    {% if post.updated %}
+    {% if post.lastUpdated() %}
-    <lastmod>{{ post.updated.toISOString() }}</lastmod>
+    <lastmod>{{ post.lastUpdated() }}</lastmod>
     {% elif post.date %}
-    <lastmod>{{ post.date.toISOString() }}</lastmod>
+    <lastmod>{{ post.date }}</lastmod>
     {% endif %}
   </url>
   {% endfor %}

themes/typing/scripts/sitemap/generator.js

@@ -2,6 +2,7 @@
 
 const nanomatch = require('nanomatch')
 const template = require('./template')
+const moment = require('moment')
 
 module.exports = function (locals) {
   const config = this.config
@@ -18,11 +19,16 @@ module.exports = function (locals) {
       return post.sitemap !== false && !isMatch(post.source, skipRenderList)
     })
     .sort((a, b) => {
-      return b.updated - a.updated
+      return b.date - a.date
     })
     .map((post) => ({
       ...post,
-      permalink: post.permalink.replace('index.html', '')
+      permalink: post.permalink.replace('index.html', ''),
+      date: moment(post.date).format('YYYY-MM-DD[T00:00:00.000Z]'),
+      lastUpdated: () => {
+        if (post.lastUpdated) return moment(post.lastUpdated).format('YYYY-MM-DD[T00:00:00.000Z]')
+        else return false
+      }
     }))
 
   // configuration dictionary
@@ -30,7 +36,7 @@ module.exports = function (locals) {
     config: config,
     posts: posts,
     // add the sNow variable for creation of the home page and potential tags/cats
-    sNow: new Date().toISOString()
+    sNow: moment().format('YYYY-MM-DD[T00:00:00.000Z]')
   }
 
   // add tags array available in the template

themes/typing/scripts/sitemap/index.js

@@ -1,11 +1,11 @@
+'use strict'
+/* global hexo */
+
 /*
 * Add sitemap.xml
 * Based on https://github.com/hexojs/hexo-generator-sitemap/pull/26
 */
 
-/* global hexo */
-'use strict'
-
 const pathFn = require('path')
 
 const config = hexo.config.sitemap = Object.assign({

themes/typing/scripts/sitemap/template.js

@@ -2,7 +2,7 @@
 
 const pathFn = require('path')
 const fs = require('fs')
-let sitemapTmpl = ""
+let sitemapTmpl = ''
 
 module.exports = function (config) {
   if (sitemapTmpl) return sitemapTmpl