New metric: hiddenImages

front/src/css/rule.css

@@ -244,8 +244,9 @@
   margin-top: 0.5em;
 }
 .smallPreview {
-  max-height: 1.6em;
-  max-width: 4em;
+  display: block;
+  max-height: 4em;
+  max-width: 8em;
   border: 1px solid #000;
-  margin-top: 0.2em;
+  margin: 1em auto 0.2em;
 }

front/src/less/rule.less

@@ -271,8 +271,9 @@
 }
 
 .smallPreview {
-    max-height: 1.6em;
-    max-width: 4em;
+    display: block;
+    max-height: 4em;
+    max-width: 8em;
     border: 1px solid #000;
-    margin-top: 0.2em;
+    margin: 1em auto 0.2em;
 }

front/src/views/rule.html

@@ -145,9 +145,9 @@
                         <file-and-line-button file="offender.file" line="offender.line" column="offender.column"></file-and-line-button>
                     </div>
 
-                    <div ng-if="policyName === 'lazyLoadableImagesBelowTheFold'">
-                        <url-link url="offender" max-length="100"></url-link>
+                    <div ng-if="policyName === 'lazyLoadableImagesBelowTheFold' || policyName === 'hiddenImages'">
                         <img ng-src="{{offender}}" class="smallPreview checker"></img>
+                        <url-link url="offender" max-length="100"></url-link>
                     </div>
 
                     <div ng-if="policyName === 'notFound' || policyName === 'closedConnections' || policyName === 'multipleRequests' || policyName === 'cachingDisabled' || policyName === 'cachingNotSpecified'">

lib/metadata/policies.js

@@ -959,13 +959,22 @@ var policies = {
     },
     "lazyLoadableImagesBelowTheFold": {
         "tool": "phantomas",
-        "label": "Not lazyloaded images",
+        "label": "Below the fold images",
         "message": "<p>This is the number of images displayed below the fold that could be lazy-loaded. This is an excellent way to accelerate the loading time of an heavy page.</p><p>I recommend using <a href=\"https://github.com/vvo/lazyload\" target=\"_blank\">this lazyloader</a>.</p>",
         "isOkThreshold": 1,
         "isBadThreshold": 12,
         "isAbnormalThreshold": 30,
         "hasOffenders": true
     },
+    "hiddenImages": {
+        "tool": "phantomas",
+        "label": "Hidden images",
+        "message": "<p>List of all images that have a display:none property, or one of their parents. These images are loaded by the browser even if they're not visible. You might be able to find a way to lazy-load them, only when they get visible.</p><p>Trackers are an exception, you'd better hide them.</p>",
+        "isOkThreshold": 3,
+        "isBadThreshold": 12,
+        "isAbnormalThreshold": 30,
+        "hasOffenders": true
+    },
     "cachingDisabled": {
         "tool": "phantomas",
         "label": "Caching disabled",

lib/metadata/scoreProfileGeneric.json

@@ -17,7 +17,8 @@
                 "notFound": 3,
                 "multipleRequests": 2,
                 "smallRequests": 1,
-                "lazyLoadableImagesBelowTheFold": 2
+                "lazyLoadableImagesBelowTheFold": 2,
+                "hiddenImages": 1
             }
         },
         "domComplexity": {

lib/tools/phantomas/custom_modules/modules/domHiddenYLT/domHiddenYLT.js

@@ -3,21 +3,23 @@
  */
 /* global document: true, Node: true, window: true */
 
-exports.version = '0.1.a';
+exports.version = '1.0.a';
 
 exports.module = function(phantomas) {
     'use strict';
 
     // total length of HTML of hidden elements (i.e. display: none)
     phantomas.setMetric('hiddenContentSize'); // @desc the size of content of hidden elements on the page (with CSS display: none) @offenders
+    phantomas.setMetric('hiddenImages'); // @desc number of hidden images that can be lazy-loaded @offenders
 
     // HTML size
     phantomas.on('report', function() {
         phantomas.evaluate(function() {
             (function(phantomas) {
-                phantomas.spyEnabled(false, 'checking the hiddenContentSize');
+                var runner = new phantomas.nodeRunner(),
+                    lazyLoadableImages = {};
 
-                var runner = new phantomas.nodeRunner();
+                phantomas.spyEnabled(false, 'analyzing hidden content');
 
                 runner.walk(document.body, function(node, depth) {
                     switch (node.nodeType) {
@@ -36,6 +38,29 @@ exports.module = function(phantomas) {
                                     }
                                 }
 
+                                // count hidden images that can be lazy loaded (issue #524)
+                                var images = [];
+                                if (node.tagName === 'IMG') {
+                                    images = [node];
+                                } else if (typeof node.querySelectorAll === 'function') {
+                                    images = node.querySelectorAll('img') || [];
+                                }
+
+                                for (var i = 0, len = images.length; i < len; i++) {
+                                    var src = images[i].src,
+                                        path;
+
+                                    if (src === '' || src.indexOf('data:image') === 0) continue;
+
+                                    if (!lazyLoadableImages[src]) {
+                                        path = phantomas.getDOMPath(images[i]);
+
+                                        lazyLoadableImages[src] = {
+                                            path: path
+                                        };
+                                    }
+                                }
+
                                 // don't run for child nodes as they're hidden as well
                                 return false;
                             }
@@ -43,6 +68,15 @@ exports.module = function(phantomas) {
                     }
                 });
 
+                Object.keys(lazyLoadableImages).forEach(function(img) {
+                    var entry = lazyLoadableImages[img];
+
+                    phantomas.incrMetric('hiddenImages');
+                    phantomas.addOffender('hiddenImages', img);
+
+                    phantomas.log('hiddenImages: <%s> image (%s) is hidden and can be lazy-loaded', img, entry.path);
+                });
+
                 phantomas.spyEnabled(true);
             }(window.__phantomas));
         });