this fixes #290

src/js/contentscript-end.js

@@ -107,12 +107,15 @@ var uBlockCollapser = (function() {
     var newRequests = [];
     var pendingRequests = {};
     var pendingRequestCount = 0;
-    var srcProps = {
+    var src1stProps = {
         'embed': 'src',
         'iframe': 'src',
         'img': 'src',
         'object': 'data'
     };
+    var src2ndProps = {
+        'img': 'srcset'
+    };
 
     var PendingRequest = function(target, tagName, attr) {
         this.id = requestId++;
@@ -215,15 +218,22 @@ var uBlockCollapser = (function() {
 
     var add = function(target) {
         var tagName = target.localName;
-        var prop = srcProps[tagName];
+        var prop = src1stProps[tagName];
         if ( prop === undefined ) {
             return;
         }
         // https://github.com/chrisaljoudi/uBlock/issues/174
         // Do not remove fragment from src URL
         var src = target[prop];
-        if ( typeof src !== 'string' || src === '' ) {
-            return;
+        if ( typeof src !== 'string' || src.length === 0 ) {
+            prop = src2ndProps[tagName];
+            if ( prop === undefined ) {
+                return;
+            }
+            src = target[prop];
+            if ( typeof src !== 'string' || src.length === 0 ) {
+                return;
+            }
         }
         if ( src.lastIndexOf('http', 0) !== 0 ) {
             return;

src/js/scriptlets/element-picker.js

@@ -318,12 +318,15 @@ var netFilterFromElement = function(elem, out) {
         return;
     }
     var tagName = elem.tagName.toLowerCase();
-    if ( netFilterSources.hasOwnProperty(tagName) === false ) {
+    if ( netFilter1stSources.hasOwnProperty(tagName) === false ) {
         return;
     }
-    var src = elem[netFilterSources[tagName]];
-    if ( src.length === 0 ) {
-        return;
+    var src = elem[netFilter1stSources[tagName]];
+    if ( typeof src !== 'string' || src.length === 0 ) {
+        src = elem[netFilter2ndSources[tagName]];
+        if ( typeof src !== 'string' || src.length === 0 ) {
+            return;
+        }
     }
     // Remove fragment
     var pos = src.indexOf('#');
@@ -346,13 +349,17 @@ var netFilterFromElement = function(elem, out) {
     netFilterFromUnion(src, out);
 };
 
-var netFilterSources = {
+var netFilter1stSources = {
      'embed': 'src',
     'iframe': 'src',
        'img': 'src',
     'object': 'data'
 };
 
+var netFilter2ndSources = {
+       'img': 'srcset'
+};
+
 /******************************************************************************/
 
 // Extract the best possible cosmetic filter, i.e. as specific as possible.
@@ -529,13 +536,17 @@ var elementsFromFilter = function(filter) {
         return out;
     }
 
-    var props = netFilterSources;
-    var elems = document.querySelectorAll(Object.keys(props).join());
+    var src1stProps = netFilter1stSources;
+    var src2ndProps = netFilter2ndSources;
+    var elems = document.querySelectorAll(Object.keys(src1stProps).join());
     var i = elems.length;
     var elem, src;
     while ( i-- ) {
         elem = elems[i];
-        src = elem[props[elem.tagName.toLowerCase()]];
+        src = elem[src1stProps[elem.localName]];
+        if ( typeof src !== 'string' || src.length === 0 ) {
+            src = elem[src2ndProps[elem.localName]];
+        }
         if ( src && reFilter.test(src) ) {
             out.push(elem);
         }