New metric: hiddenImages

2015-09-18 18:51:41 +02:00
parent 46c2d8c49e
commit d32b9f78a4
6 changed files with 59 additions and 13 deletions
@@ -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));
        });