Merge pull request samsonjs#59 from samsonjs/Issue56_BugInWeekNumber

Fixes samsonjs#56 (Bug in %U)
michaeljayt · Mar 29, 2015 · fe2892e · fe2892e
2 parents 22ddd89 + aee0e19
commit fe2892e
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Showing 2 changed files with 7 additions and 2 deletions.
diff --git a/strftime.js b/strftime.js
@@ -595,8 +595,10 @@
             else
                 weekday--;
         }
-        var firstDayOfYear = new Date(date.getFullYear(), 0, 1),
-            yday = (date - firstDayOfYear) / 86400000,
+
+        var firstDayOfYearUtc = Date.UTC(date.getFullYear(), 0, 1),
+            dateUtc = Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()),
+            yday = Math.floor((dateUtc - firstDayOfYearUtc) / 86400000),
             weekNum = (yday + 7 - weekday) / 7;
 
         return Math.floor(weekNum);

diff --git a/test.js b/test.js
@@ -115,6 +115,9 @@ assert.format('%z', null, '+0000');
 assert.format('%:z', null, '+00:00');
 assert.format('%%', '%'); // any other char
 assert.format('%F %T', null, '1970-01-01 00:00:00', new Date(0));
+assert.format('%U', '13', "12", (new Date('03-26-2017 00:00:00')));
+assert.format('%U', '13', null, (new Date('03-27-2017 00:00:00')));
+assert.format('%U', '14', "13", (new Date('04-02-2017 00:00:00')));
 ok('GMT');