Add wholeMonths interval to weeksOfMonthByDay

README.md

@@ -213,6 +213,13 @@ var valentines = moment.recur().every(14).daysOfMonth()
 // The following matches every 1st and 3rd Thursday of the month.
 cal = moment.recur().every("Thursday").daysOfWeek()
                     .every([0, 2]).weeksOfMonthByDay();
+
+// A wholeMonth interval is available for combining with
+// the daysOfWeek and weekOfMonthByDay to achieve "nth weekday every nth months" recurrences.
+// The following matches every 1st and 3rd Thursday every 2 months.
+cal = moment.recur().every("Thursday").daysOfWeek()
+                    .every([0, 2]).weeksOfMonthByDay()
+                    .every(2).wholeMonths();                    
 ```
 
 

moment-recur.js

@@ -27,8 +27,12 @@
                 }
             }
 
+			if (measure !== 'wholeMonths') {
+				measure = measure.toLowerCase();
+			}
+
             return {
-                measure: measure.toLowerCase(),
+                measure: measure,
                 units: units
             };
         }
@@ -37,10 +41,20 @@
             // Get the difference between the start date and the provided date,
             // using the required measure based on the type of rule'
             var diff = null;
+
+            // if the type is wholeMonths use the whole month
             if( date.isBefore(start) ) {
-                diff = start.diff(date, type, true);
+            	if( type == 'wholeMonths' ) {
+            		diff = start.diff(date, 'month');
+            	} else {
+                	diff = start.diff(date, type, true);
+                }
             } else {
-                diff = date.diff(start, type, true);
+            	if( type == 'wholeMonths' ) {
+            		diff = date.diff(start, 'month');
+            	} else {
+                	diff = date.diff(start, type, true);
+                }
             }
             if( type == 'days') {
                 // if we are dealing with days, we deal with whole days only.
@@ -184,6 +198,7 @@
             "days": "interval",
             "weeks": "interval",
             "months": "interval",
+            "wholeMonths": "interval",
             "years": "interval",
             "daysOfWeek": "calendar",
             "daysOfMonth": "calendar",
@@ -198,6 +213,7 @@
             "days": "day",
             "weeks": "week",
             "months": "month",
+            "wholeMonths": "wholeMonth",
             "years": "year",
             "daysOfWeek": "dayOfWeek",
             "daysOfMonth": "dayOfMonth",
@@ -252,6 +268,10 @@
             if (rule.measure === 'weeksOfMonthByDay' && !this.hasRule('daysOfWeek')) {
                 throw Error("weeksOfMonthByDay must be combined with daysOfWeek");
             }
+
+            if (rule.measure === 'wholeMonths' && (!this.hasRule('daysOfWeek') || !this.hasRule('weeksOfMonthByDay'))) {
+            	throw Error("wholeMonths must be combined with weeksOfMonthByDay and daysOfWeek");
+            }
 
             // Remove existing rule based on measure
             for (var i = 0; i < this.rules.length; i++) {
@@ -380,6 +400,9 @@
 
                 case "month":
                     return "months";
+
+                case "wholeMonth":
+                	return "wholeMonths";
 
                 case "year":
                     return "years";