Allow empty string to be passed to formAction

Author: sebmarkbage

packages/react-dom-bindings/src/shared/DOMProperty.js

@@ -636,7 +636,19 @@ properties[xlinkHref] = new PropertyInfoRecord(
   false, // removeEmptyString
 );
 
-['src', 'href', 'action', 'formAction'].forEach(attributeName => {
+const formAction = 'formAction';
+// $FlowFixMe[invalid-constructor] Flow no longer supports calling new on functions
+properties[formAction] = new PropertyInfoRecord(
+  'formAction',
+  STRING,
+  false, // mustUseProperty
+  'formaction', // attributeName
+  null, // attributeNamespace
+  true, // sanitizeURL
+  false, // removeEmptyString
+);
+
+['src', 'href', 'action'].forEach(attributeName => {
   // $FlowFixMe[invalid-constructor] Flow no longer supports calling new on functions
   properties[attributeName] = new PropertyInfoRecord(
     attributeName,

packages/react-dom/src/__tests__/ReactDOMComponent-test.js

@@ -533,29 +533,17 @@ describe('ReactDOMComponent', () => {
         expect(node.hasAttribute('action')).toBe(false);
       });
 
-      it('should not add an empty formAction attribute', () => {
+      it('allows empty string of a formAction to override the default of a parent', () => {
         const container = document.createElement('div');
-        expect(() =>
-          ReactDOM.render(<button formAction="" />, container),
-        ).toErrorDev(
-          'An empty string ("") was passed to the formAction attribute. ' +
-            'To fix this, either do not render the element at all ' +
-            'or pass null to formAction instead of an empty string.',
-        );
-        const node = container.firstChild;
-        expect(node.hasAttribute('formAction')).toBe(false);
-
-        ReactDOM.render(<button formAction="abc" />, container);
-        expect(node.hasAttribute('formAction')).toBe(true);
-
-        expect(() =>
-          ReactDOM.render(<button formAction="" />, container),
-        ).toErrorDev(
-          'An empty string ("") was passed to the formAction attribute. ' +
-            'To fix this, either do not render the element at all ' +
-            'or pass null to formAction instead of an empty string.',
+        ReactDOM.render(
+          <form action="hello">
+            <button formAction="" />,
+          </form>,
+          container,
         );
-        expect(node.hasAttribute('formAction')).toBe(false);
+        const node = container.firstChild.firstChild;
+        expect(node.hasAttribute('formaction')).toBe(true);
+        expect(node.getAttribute('formaction')).toBe('');
       });
 
       it('should not filter attributes for custom elements', () => {

packages/shared/ReactFeatureFlags.js

@@ -172,7 +172,7 @@ export const disableInputAttributeSyncing = false;
 // Filter certain DOM attributes (e.g. src, href) if their values are empty
 // strings. This prevents e.g. <img src=""> from making an unnecessary HTTP
 // request for certain browsers.
-export const enableFilterEmptyStringAttributesDOM = false;
+export const enableFilterEmptyStringAttributesDOM = __EXPERIMENTAL__;
 
 // Changes the behavior for rendering custom elements in both server rendering
 // and client rendering, mostly to allow JSX attributes to apply to the custom