Add fieldset/util and tests

Author: tcannonfodder

package.json

@@ -13,7 +13,8 @@
     "./request-processing": "./src/request-processing.js",
     "./plugins/mrujs": "./src/plugins/mrujs.js",
     "./utils": "./src/util.js",
-    "./fieldset/rendering": "./src/fieldset/rendering.js"
+    "./fieldset/rendering": "./src/fieldset/rendering.js",
+    "./fieldset/util": "./src/fieldset/util.js"
   },
   "scripts": {
     "start": "web-dev-server --open demo/ --node-resolve",

src/fieldset/util.js

@@ -0,0 +1,78 @@
+import {
+  skipChangeValidation,
+  skipFocusoutValidation,
+  skipValidation
+} from "../element-utilities.js"
+
+/**
+ * Checks that there is at least N values in the `FormData` for the given
+ * `fieldName` in the `fieldset`'s form.
+ * @param {FieldsetElement} fieldset
+ * @param {string} fieldName
+ * @param {integer} minimum
+ * @return {boolean} if there is at least 1 record for `fieldName` in the fieldset form's `FormData`
+ */
+export function minimumCountOfFieldNameSelected(fieldset, fieldName, minimum) {
+  const formData = new FormData(fieldset.form)
+  return formData.getAll(fieldName).length >= minimum
+}
+
+/**
+ * Helper method to check if the the `ChangeEvent` is inside of
+ * its target.
+ *
+ * @param {ChangeEvent} event
+ * @return {boolean}
+ */
+export function isChangeEventForTarget(event) {
+  return event.currentTarget == event.target
+}
+
+/**
+ * Helper method to check that the the `FocusEvent` is inside of
+ * its target.
+ *
+ * @param {FocusEvent} event
+ * @return {boolean}
+ */
+export function isFocusEventInsideTarget(event) {
+  return event.currentTarget.contains(event.relatedTarget)
+}
+
+/**
+ * Helper method to check if the `change` event should be skipped by checking:
+ * - {@link isChangeEventForTarget}
+ * - {@link skipChangeValidation}
+ * - {@link skipValidation}
+ *
+ * @param {Event} event
+ * @returns {boolean} true if the `change` event should be skipped
+ */
+export function skipFieldsetChangeEvent(event) {
+  if(isChangeEventForTarget(event)){ return true }
+
+  const element = event.currentTarget
+  if(skipChangeValidation(element)){ return true }
+  if(skipValidation(element)){ return true }
+
+  return false
+}
+
+/**
+ * Helper method to check if the `focousout` event should be skipped by checking:
+ * - {@link isFocusEventInsideTarget}
+ * - {@link skipFocusoutValidation}
+ * - {@link skipValidation}
+ *
+ * @param {Event} event
+ * @returns {boolean} true if the `focousout` event should be skipped
+ */
+export function skipFieldsetFocusoutEvent(event) {
+  if(isFocusEventInsideTarget(event)){ return true}
+
+  const element = event.currentTarget
+  if(skipFocusoutValidation(element)){ return true }
+  if(skipValidation(element)){ return true }
+
+  return false
+}