--- /dev/null
+'use strict';
+
+var getMonth = Date.prototype.getMonth;
+
+module.exports = function () {
+ switch (getMonth.call(this)) {
+ case 1:
+ return this.getFullYear() % 4 ? 28 : 29;
+ case 3:
+ case 5:
+ case 8:
+ case 10:
+ return 30;
+ default:
+ return 31;
+ }
+};