Install global submit listener only when amp-form extension is registered

src/document-submit.js

@@ -23,12 +23,25 @@ import {
 } from './url';
 import {Services} from './services';
 import {dev, user} from './log';
+import {isExtensionScriptInNode} from './element-service';
 
 /**
  * @param {!./service/ampdoc-impl.AmpDoc} ampdoc
+ * @return {!Promise}
  */
 export function installGlobalSubmitListenerForDoc(ampdoc) {
-  ampdoc.getRootNode().addEventListener('submit', onDocumentFormSubmit_, true);
+  // Register global submit event listener only if the amp-form
+  // extension is used. Allowing the usage of native forms, otherwise.
+  return isExtensionScriptInNode(
+      ampdoc.win,
+      ampdoc.getHeadNode(),
+      'amp-form')
+      .then(isAmpFormExtension => {
+        if (isAmpFormExtension) {
+          ampdoc.getRootNode().addEventListener(
+              'submit', onDocumentFormSubmit_, true);
+        }
+      });
 }
 
 

src/element-service.js

@@ -203,6 +203,32 @@ export function extensionScriptsInNode(head) {
   return scripts;
 }
 
+/**
+ * Waits for body to be present then verifies that an extension script is
+ * present in head for installation.
+ * @param {!Window} win
+ * @param {HTMLHeadElement|Element|ShadowRoot} head
+ * @param {string} extensionId
+ * @return {!Promise<boolean>}
+ */
+export function isExtensionScriptInNode(win, head, extensionId) {
+  return dom.waitForBodyPromise(win.document)
+      .then(() => {
+        return extensionScriptInNode(head, extensionId);
+      });
+}
+
+/**
+ * Verifies that an extension script is present in head for
+ * installation.
+ * @param {HTMLHeadElement|Element|ShadowRoot} head
+ * @param {string} extensionId
+ * @private
+ */
+function extensionScriptInNode(head, extensionId) {
+  return extensionScriptsInNode(head).includes(extensionId);
+}
+
 /**
  * Waits for an extension if its script is present
  * @param {!Window} win
@@ -222,7 +248,7 @@ function waitForExtensionIfPresent(win, extension, head) {
 
   // TODO(jpettitt) investigate registerExtension to short circuit
   // the dom call in extensionScriptsInNode()
-  if (!extensionScriptsInNode(head).includes(extension)) {
+  if (!extensionScriptInNode(head, extension)) {
     return Promise.resolve();
   }
 

test/functional/test-document-submit.js

@@ -15,7 +15,7 @@
  */
 
 import {Services} from '../../src/services';
-import {onDocumentFormSubmit_} from '../../src/document-submit';
+import {installGlobalSubmitListenerForDoc, onDocumentFormSubmit_} from '../../src/document-submit';
 
 describe('test-document-submit onDocumentFormSubmit_', () => {
   let sandbox;
@@ -46,6 +46,49 @@ describe('test-document-submit onDocumentFormSubmit_', () => {
     sandbox.restore();
   });
 
+  describe('installGlobalSubmitListenerForDoc', () => {
+    let ampdoc;
+    let headNode;
+    let rootNode;
+    beforeEach(() => {
+      headNode = document.createElement('head');
+      rootNode = document.createElement('html');
+      ampdoc = {
+        getHeadNode: () => headNode,
+        getRootNode: () => rootNode,
+        win: {document: {documentElement: {body: {}}}},
+      };
+    });
+
+    /**
+     * @param {string} extension
+     */
+    const createScript = extension => {
+      const script = document.createElement('script');
+      script.setAttribute('src',
+          'https://cdn.ampproject.org/v0/' + extension + '-0.1.js');
+      script.setAttribute('custom-element', extension);
+      return script;
+    };
+
+    it('should not register submit listener if amp-form is not registered.',
+        () => {
+          ampdoc.getHeadNode().appendChild(createScript('amp-list'));
+          sandbox.spy(rootNode, 'addEventListener');
+          installGlobalSubmitListenerForDoc(ampdoc).then(() => {
+            expect(rootNode.addEventListener).not.to.have.been.called;
+          });
+        });
+
+    it('should register submit listener if amp-form extension is registered.',
+        () => {
+          ampdoc.getHeadNode().appendChild(createScript('amp-form'));
+          sandbox.spy(rootNode, 'addEventListener');
+          installGlobalSubmitListenerForDoc(ampdoc).then(() => {
+            expect(rootNode.addEventListener).called;
+          });
+        });
+  });
 
   it('should check target and action attributes', () => {
     tgt.removeAttribute('action');

test/functional/test-element-service.js

@@ -21,6 +21,7 @@ import {
   getElementServiceIfAvailable,
   getElementServiceIfAvailableForDoc,
   getElementServiceIfAvailableForDocInEmbedScope,
+  isExtensionScriptInNode,
 } from '../../src/element-service';
 import {
   installServiceInEmbedScope,
@@ -330,6 +331,19 @@ describes.realWin('in single ampdoc', {
         expect(service).to.deep.equal({str: 'fake1'});
       });
     });
+
+    it('isExtensionScriptInNode', () => {
+      const extension = document.createElement('script');
+      extension.setAttribute('custom-element', 'amp-form');
+      extension.setAttribute('src', 'https://cdn.ampproject.org/v0/amp-form-0.1.js');
+      ampdoc.getHeadNode().appendChild(extension);
+      return isExtensionScriptInNode(
+          ampdoc.win,
+          ampdoc.getHeadNode(),
+          'amp-form').then(isAmpForminNode => {
+        expect(isAmpForminNode).to.equal(true);
+      });
+    });
   });
 });