Adding intial pass of heuristics for iframe validity

src/annotator/util/frame-util.js

@@ -2,7 +2,7 @@
 
 // Find all iframes within this iframe only
 function findFrames (container) {
-  var frames = Array.from(container.getElementsByTagName('iframe'));
+  const frames = Array.from(container.getElementsByTagName('iframe'));
   return frames.filter(isValid);
 }
 
@@ -13,13 +13,13 @@ function hasHypothesis (iframe) {
 
 // Inject embed.js into the iframe
 function injectHypothesis (iframe, scriptUrl, config) {
-  var configElement = document.createElement('script');
+  const configElement = document.createElement('script');
   configElement.className = 'js-hypothesis-config';
   configElement.type = 'application/json';
   configElement.innerText = JSON.stringify(config);
 
-  var src = scriptUrl;
-  var embedElement = document.createElement('script');
+  const src = scriptUrl;
+  const embedElement = document.createElement('script');
   embedElement.className = 'js-hypothesis-embed';
   embedElement.async = true;
   embedElement.src = src;
@@ -37,10 +37,27 @@ function isAccessible (iframe) {
   }
 }
 
-// Check if this is an iframe that we want to inject embed.js into
+
+/**
+ * Check if the frame elements being considered for injection have the
+ * basic heuristics for content that a user might want to annotate.
+ *  Rules:
+ *    - avoid our client iframe
+ *    - iframe should be sizeable - to avoid the small advertisement and social plugins
+ *
+ * @param  {HTMLIFrameElement} iframe the frame being checked
+ * @returns {boolean}   result of our validity checks
+ */
 function isValid (iframe) {
-  // Currently only checks if it's not the h-sidebar
-  return iframe.className !== 'h-sidebar-iframe';
+
+  const isNotClientFrame = !iframe.classList.contains('h-sidebar-iframe');
+
+  const frameRect = iframe.getBoundingClientRect();
+  const MIN_WIDTH = 150;
+  const MIN_HEIGHT = 150;
+  const hasSizableContainer = frameRect.width > MIN_WIDTH && frameRect.height > MIN_HEIGHT;
+
+  return isNotClientFrame && hasSizableContainer;
 }
 
 function isDocumentReady (iframe, callback) {
@@ -68,7 +85,6 @@ module.exports = {
   hasHypothesis: hasHypothesis,
   injectHypothesis: injectHypothesis,
   isAccessible: isAccessible,
-  isValid: isValid,
   isLoaded: isLoaded,
   isDocumentReady: isDocumentReady,
 };

src/annotator/util/test/frame-util-test.js

+'use strict';
+
+const frameUtil = require('../frame-util');
+
+describe('frameUtil', function () {
+  describe('findFrames', function () {
+
+    let container;
+
+    const _addFrameToContainer = (options={})=>{
+      const frame = document.createElement('iframe');
+      frame.className = options.className || '';
+      frame.style.height = `${(options.height || 150)}px`;
+      frame.style.width = `${(options.width || 150)}px`;
+      container.appendChild(frame);
+      return frame;
+    };
+
+    beforeEach(function () {
+      container = document.createElement('div');
+      document.body.appendChild(container);
+    });
+
+    afterEach(function () {
+      container.remove();
+    });
+
+    it('should find valid frames', function () {
+
+      let foundFrames = frameUtil.findFrames(container);
+
+      assert.lengthOf(foundFrames, 0, 'no frames appended so none should be found');
+
+      const frame1 = _addFrameToContainer();
+      const frame2 = _addFrameToContainer();
+
+      foundFrames = frameUtil.findFrames(container);
+
+      assert.deepEqual(foundFrames, [frame1, frame2], 'appended frames should be found');
+    });
+
+    it('should not find small frames', function () {
+
+      // add frames that are small in both demensions
+      _addFrameToContainer({width: 140});
+      _addFrameToContainer({height: 140});
+
+      const foundFrames = frameUtil.findFrames(container);
+
+      assert.lengthOf(foundFrames, 0, 'frames with small demensions should not be found');
+    });
+
+    it('should not find hypothesis frames', function () {
+
+      _addFrameToContainer({className: 'h-sidebar-iframe other-class-too'});
+
+      const foundFrames = frameUtil.findFrames(container);
+
+      assert.lengthOf(foundFrames, 0, 'frames with hypothesis className should not be found');
+    });
+  });
+});