Listen for removed inputs and unregister them

src/index.ts

@@ -518,13 +518,17 @@ export class ValidationService {
     /**
      * Scans document for all validation message <span> generated by ASP.NET Core MVC, then tracks them.
      */
-    private scanMessages(root: ParentNode) {
+    private scanMessages(root: ParentNode, remove: boolean = false) {
         /* If a validation span explicitly declares a form, we group the span with that form. */
         let validationMessageElements = Array.from(root.querySelectorAll<HTMLElement>('span[form]'));
         for (let span of validationMessageElements) {
             let form = document.getElementById(span.getAttribute('form'));
             if (form) {
-                this.pushValidationMessageSpan(form, span);
+                if (remove) {
+                    this.removeValidationMessageSpan(form, span);
+                } else {
+                    this.pushValidationMessageSpan(form, span);
+                }
             }
         }
 
@@ -540,7 +544,11 @@ export class ValidationService {
             let validationMessageElements = Array.from(form.querySelectorAll<HTMLElement>('[data-valmsg-for]'));
 
             for (let span of validationMessageElements) {
-                this.pushValidationMessageSpan(form, span);
+                if (remove) {
+                    this.removeValidationMessageSpan(form, span);
+                } else {
+                    this.pushValidationMessageSpan(form, span);
+                }
             }
         }
     }
@@ -557,6 +565,19 @@ export class ValidationService {
         }
     }
 
+    private removeValidationMessageSpan(form: HTMLElement, span: HTMLElement) {
+        let formId = this.getElementUID(form);
+        let name = `${formId}:${span.getAttribute('data-valmsg-for')}`;
+        let spans = this.messageFor[name] || (this.messageFor[name] = []);
+        let index = spans.indexOf(span);
+        if (index >= 0) {
+            spans.splice(index, 1);
+        }
+        else {
+            this.logger.log("Validation element for '%s' was already removed", name, span);
+        }
+    }
+
     /**
      * Given attribute map for an HTML input, returns the validation directives to be executed.
      * @param attributes
@@ -649,7 +670,10 @@ export class ValidationService {
 
         for (let i = 0; i < formInputUIDs.length; i++) {
             let inputUID = formInputUIDs[i];
-            formValidators.push(this.validators[inputUID]);
+            const validator = this.validators[inputUID];
+            if (validator) {
+                formValidators.push(validator);
+            }
         }
 
         let tasks = formValidators.map(factory => factory());
@@ -895,6 +919,20 @@ export class ValidationService {
         this.elementEvents[formUID] = cb;
     }
 
+    private untrackFormInput(form: HTMLFormElement, inputUID: string) {
+        let formUID = this.getElementUID(form);
+        if (!this.formInputs[formUID]) {
+            this.formInputs[formUID] = [];
+        }
+        let indexToRemove = this.formInputs[formUID].indexOf(inputUID);
+        if (indexToRemove >= 0) {
+            this.formInputs[formUID].splice(indexToRemove, 1);
+        }
+        else {
+            this.logger.log("Form input for UID '%s' was already removed", inputUID);
+        }
+    }
+
     /**
      * Adds an input element to be managed and validated by the service.
      * Triggers a debounced live validation when input value changes.
@@ -935,10 +973,22 @@ export class ValidationService {
         this.elementEvents[uid] = cb;
     }
 
+    removeInput(input: ValidatableElement) {
+        let uid = this.getElementUID(input);
+
+        delete this.summary[uid];
+        delete this.elementEvents[uid];
+        delete this.validators[uid];
+
+        if (input.form) {
+            this.untrackFormInput(input.form, uid);
+        }
+    }
+
     /**
      * Scans the entire document for input elements to be validated.
      */
-    private scanInputs(root: ParentNode) {
+    private scanInputs(root: ParentNode, remove: boolean = false) {
         let inputs = Array.from(root.querySelectorAll<ValidatableElement>(validatableSelector('[data-val="true"]')));
 
         // querySelectorAll does not include the root element itself.
@@ -949,7 +999,12 @@ export class ValidationService {
 
         for (let i = 0; i < inputs.length; i++) {
             let input = inputs[i];
-            this.addInput(input);
+            if (remove) {
+                this.removeInput(input);
+            }
+            else {
+                this.addInput(input);
+            }
         }
     }
 
@@ -1210,10 +1265,10 @@ export class ValidationService {
     /**
      * Scans the provided root element for any validation directives and attaches behavior to them.
      */
-    scan(root: ParentNode) {
+    scan(root: ParentNode, remove: boolean = false) {
         this.logger.log('Scanning', root);
-        this.scanMessages(root);
-        this.scanInputs(root);
+        this.scanMessages(root, remove);
+        this.scanInputs(root, remove);
     }
 
     /**
@@ -1243,6 +1298,13 @@ export class ValidationService {
                     this.scan(node);
                 }
             }
+            for (let i = 0; i < mutation.removedNodes.length; i++) {
+                let node = mutation.removedNodes[i];
+                this.logger.log('Removed node', node);
+                if (node instanceof HTMLElement) {
+                    this.scan(node, true);
+                }
+            }
         } else if (mutation.type === 'attributes') {
             if (mutation.target instanceof HTMLElement) {
                 const oldValue = mutation.oldValue ?? '';