Issue #3278415 by nod_, lauriii, catch, Wim Leers, longwave, xjm, claudiu.cristea: Remove usages of the JavaScript ES6 build step, the build step itself, and associated dev dependencies

1 files changed, 41 insertions, 21 deletions

diff --git a/core/misc/timezone.js b/core/misc/timezone.js
index 053182bfbb4d..a8c1a5f7ac58 100644
--- a/core/misc/timezone.js
+++ b/core/misc/timezone.js
@@ -1,64 +1,84 @@
 /**
-* DO NOT EDIT THIS FILE.
-* See the following change record for more information,
-* https://www.drupal.org/node/2815083
-* @preserve
-**/
+ * @file
+ * Timezone detection.
+ */
 
 (function ($, Drupal) {
+  /**
+   * Set the client's system time zone as default values of form fields.
+   *
+   * @type {Drupal~behavior}
+   */
   Drupal.behaviors.setTimezone = {
     attach(context, settings) {
       const timezone = once('timezone', '.timezone-detect', context);
-
       if (timezone.length) {
         const tz = new Intl.DateTimeFormat().resolvedOptions().timeZone;
-
+        // Ensure that the timezone value returned by the browser is supported
+        // by the server.
         if (tz && $(timezone).find(`option[value="${tz}"]`).length) {
-          timezone.forEach(item => {
+          timezone.forEach((item) => {
             item.value = tz;
           });
           return;
         }
 
         const dateString = Date();
+        // In some client environments, date strings include a time zone
+        // abbreviation, between 3 and 5 letters enclosed in parentheses,
+        // which can be interpreted by PHP.
         const matches = dateString.match(/\(([A-Z]{3,5})\)/);
         const abbreviation = matches ? matches[1] : 0;
+
+        // For all other client environments, the abbreviation is set to "0"
+        // and the current offset from UTC and daylight saving time status are
+        // used to guess the time zone.
         const dateNow = new Date();
         const offsetNow = dateNow.getTimezoneOffset() * -60;
+
+        // Use January 1 and July 1 as test dates for determining daylight
+        // saving time status by comparing their offsets.
         const dateJan = new Date(dateNow.getFullYear(), 0, 1, 12, 0, 0, 0);
         const dateJul = new Date(dateNow.getFullYear(), 6, 1, 12, 0, 0, 0);
         const offsetJan = dateJan.getTimezoneOffset() * -60;
         const offsetJul = dateJul.getTimezoneOffset() * -60;
-        let isDaylightSavingTime;
 
+        let isDaylightSavingTime;
+        // If the offset from UTC is identical on January 1 and July 1,
+        // assume daylight saving time is not used in this time zone.
         if (offsetJan === offsetJul) {
           isDaylightSavingTime = '';
-        } else if (Math.max(offsetJan, offsetJul) === offsetNow) {
+        }
+        // If the maximum annual offset is equivalent to the current offset,
+        // assume daylight saving time is in effect.
+        else if (Math.max(offsetJan, offsetJul) === offsetNow) {
           isDaylightSavingTime = 1;
-        } else {
+        }
+        // Otherwise, assume daylight saving time is not in effect.
+        else {
           isDaylightSavingTime = 0;
         }
 
+        // Submit request to the system/timezone callback and set the form
+        // field to the response time zone. The client date is passed to the
+        // callback for debugging purposes. Submit a synchronous request to
+        // avoid database errors associated with concurrent requests
+        // during install.
         const path = `system/timezone/${abbreviation}/${offsetNow}/${isDaylightSavingTime}`;
         $.ajax({
           async: false,
           url: Drupal.url(path),
-          data: {
-            date: dateString
-          },
+          data: { date: dateString },
           dataType: 'json',
-
           success(data) {
             if (data) {
-              document.querySelectorAll('.timezone-detect').forEach(item => {
+              document.querySelectorAll('.timezone-detect').forEach((item) => {
                 item.value = data;
               });
             }
-          }
-
+          },
         });
       }
-    }
-
+    },
   };
-})(jQuery, Drupal);
\ No newline at end of file
+})(jQuery, Drupal);