Add emtpy value checks to update behavior (#12)

Author: Griffon-Weglot

src/jquery.submitable.js

@@ -66,7 +66,9 @@
             let enable = true;
             if (this.options.strategy === $.fn.submitable.strategy.UPDATE) {
                 enable = this.computeValues() !== this.options.defaultValues;
-            } else if (this.options.strategy === $.fn.submitable.strategy.NOT_EMPTY) {
+            }
+
+            if (this.options.strategy === $.fn.submitable.strategy.NOT_EMPTY || (enable && $.fn.submitable.strategy.UPDATE)) {
                 this.$element.find(":input[required]:not([type=hidden]):not([disabled]), select[required]:not([disabled]), radio:not([disabled])").each((index, element) => {
                     if (element.value === '') {
                         enable = false