Added missing knockoutjs checked.js binding

vendors/knockout/src/binding/defaultBindings/checked.js

@@ -0,0 +1,57 @@
+(()=>{
+
+ko.bindingHandlers['checked'] = {
+    'after': ['value', 'attr'],
+    'init': function (element, valueAccessor, allBindings) {
+        var isCheckbox = element.type == "checkbox",
+            isRadio = element.type == "radio";
+
+        // Only bind to check boxes and radio buttons
+        if (isCheckbox || isRadio) {
+            const checkedValue = ko.pureComputed(()=>{
+                if (isRadio) {
+                    return allBindings['has']('value')
+                        ? ko.utils.unwrapObservable(allBindings.get('value'))
+                        : element.value;
+                }
+            });
+
+            // Set up two computeds to update the binding:
+
+            // The first responds to element clicks
+            element.addEventListener("click", () => {
+                // When we're first setting up this computed, don't change any model state.
+                if (ko.dependencyDetection.isInitial()) {
+                    return;
+                }
+
+                // This updates the model value from the view value.
+                // It runs in response to DOM events (click) and changes in checkedValue.
+                var isChecked = element.checked;
+
+                // We can ignore unchecked radio buttons, because some other radio
+                // button will be checked, and that one can take care of updating state.
+                // Also ignore value changes to an already unchecked checkbox.
+                if (!isChecked && (isRadio || ko.dependencyDetection.getDependenciesCount())) {
+                    return;
+                }
+
+                var elemValue = isCheckbox ? isChecked : checkedValue(),
+                    modelValue = ko.dependencyDetection.ignore(valueAccessor);
+                ko.expressionRewriting.writeValueToProperty(modelValue, allBindings, 'checked', elemValue, true);
+            }),
+
+            // The second responds to changes in the model value (the one associated with the checked binding)
+            ko.computed(() => {
+                // This updates the view value from the model value.
+                // It runs in response to changes in the bound (checked) value.
+                var modelValue = ko.utils.unwrapObservable(valueAccessor());
+                element.checked = isCheckbox ? !!modelValue : (checkedValue() === modelValue);
+            }, null, { disposeWhenNodeIsRemoved: element });
+        }
+    }
+};
+
+ko.expressionRewriting.twoWayBindings['checked'] = true;
+
+})();