Merge 1267abb into 4539f9f

src/officialValidators/week.js

@@ -3,20 +3,41 @@
 import { parseWeek } from '../utils';
 
 // Example week: "2016-W33"
-// TODO: this needs to be improved since some years have 52 weeks
-const MAX_WEEK = 53
 export default function weekValidator(control) {
   // Special case for empty values. This is the job of the `required` validator
   if (!control.value) {
     return false;
   }
 
-  const value = control.value
-  const [year, week] = parseWeek(value)
+  const value = control.value;
+  const [year, week] = parseWeek(value);
 
   if (!year || !week) {
-    return true
+    return true;
   }
 
-  return !(0 < year && 1 <= week && week <= MAX_WEEK)
+  return !(0 < year && 1 <= week && week <= weeksInYear(year));
+}
+
+function weeksInYear(year) {
+  var d = new Date(year, 11, 31);
+  var week = getWeekNumber(d)[1];
+
+  return week == 1? getWeekNumber(d.setDate(24))[1] : week;
+}
+
+function getWeekNumber(d) {
+    // Copy date so don't modify original
+    d = new Date(+d);
+    d.setHours(0,0,0);
+    // Set to nearest Thursday: current date + 4 - current day number
+    // Make Sunday's day number 7
+    d.setDate(d.getDate() + 4 - (d.getDay()||7));
+    // Get first day of year
+    var yearStart = new Date(d.getFullYear(),0,1);
+    // Calculate full weeks to nearest Thursday
+    var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7)
+
+    // Return array of year and week number
+    return [d.getFullYear(), weekNo];
 }