add isValidDateArg

src/calendar-array.js

@@ -1,10 +1,44 @@
 class CalendarArray {
+  getCalendar(...dates) {
+    if (this.#isValidDateArg(dates)) {
+      console.log('is valid');
+    }
+  }
 
+  /*
+    Validates getCalendar arguments.
+    - sample correct arguments
+    [[2020, 3], [2012], [2007]]
+  */
+  #isValidDateArg(dates) {
+    if (dates.length > 0) {
+      for (let date of dates) {
+
+        if (!Array.isArray(date)) {
+          throw new TypeError(`type: ${typeof date} <- the argument is of the wrong type, array expected`);
+
+        } else if (date.length === 0) {
+          throw new Error(`length: ${date.length} <- array is empty`);
+        } else {
+
+          for (let value of date) {
+            if (typeof value !== 'number') {
+              throw new TypeError(`type: ${typeof value} <- invalid date type in this array of dates, expected number`);
+            }
+          }
+        }
+      }
+    } else {
+      throw new Error('Empty args array, pass an array with a date');
+    }
+
+    return true;
+  }
 }
 
 // export globals
 if (typeof module !== 'undefined') {
   module.exports = new CalendarArray();
 } else {
-  window.CalendarArray = new CalendarArray();
+  window.calendarArray = new CalendarArray();
 }