this fixes #452

src/js/contentscript-end.js

@@ -48,7 +48,7 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
     }
 
     var queriedSelectors = {};
-    var injectedSelectors = vAPI.hideCosmeticFilters || {};
+    var injectedSelectors = {};
     var classSelectors = null;
     var idSelectors = null;
     var highGenerics = null;
@@ -56,28 +56,36 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
     var nullArray = { push: function(){} };
 
     var domLoaded = function() {
+        idsFromNodeList(document.querySelectorAll('[id]'));
+        classesFromNodeList(document.querySelectorAll('[class]'));
+        retrieveGenericSelectors();
+    };
+
+    // https://github.com/gorhill/uBlock/issues/452
+    // This needs to be executed *after* the response from our query is 
+    // received, not at `DOMContentLoaded` time, or else there is a good
+    // likeliness to outrun contentscript-start.js, which may still be waiting
+    // on a response from its own query.
+    var firstRunHandler = function() {
         // https://github.com/gorhill/uBlock/issues/158
         // Ensure injected styles are enforced
         // rhill 2014-11-16: not sure this is needed anymore. Test case in
         //  above issue was fine without the line below..
         var selectors = vAPI.hideCosmeticFilters;
         if ( typeof selectors === 'object' ) {
+            injectedSelectors = selectors;
             hideElements(Object.keys(selectors).join(','));
         }
         // Add exception filters into injected filters collection, in order
         // to force them to be seen as "already injected".
         selectors = vAPI.donthideCosmeticFilters;
         if ( typeof selectors === 'object' ) {
-            for ( var selector in selectors ) {
+            for ( selector in selectors ) {
                 if ( selectors.hasOwnProperty(selector) ) {
                     injectedSelectors[selector] = true;
                 }
             }
         }
-        // Now scan content of page
-        idsFromNodeList(document.querySelectorAll('[id]'));
-        classesFromNodeList(document.querySelectorAll('[class]'));
-        retrieveGenericSelectors();
     };
 
     var retrieveGenericSelectors = function() {
@@ -103,6 +111,12 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
     };
 
     var retrieveHandler = function(selectors) {
+        // https://github.com/gorhill/uBlock/issues/452
+        // See above.
+        if ( typeof firstRunHandler === 'function' ) {
+            firstRunHandler();
+            firstRunHandler = undefined;
+        }
         //console.debug('µBlock> contextNodes = %o', contextNodes);
         if ( selectors && selectors.highGenerics ) {
             highGenerics = selectors.highGenerics;
@@ -216,7 +230,7 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
         var selector;
         while ( i-- ) {
             selector = generics[i];
-            if ( injectedSelectors[selector] !== undefined ) {
+            if ( injectedSelectors.hasOwnProperty(selector) ) {
                 continue;
             }
             injectedSelectors[selector] = true;
@@ -241,14 +255,14 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
                 if ( !attrValue ) { continue; }
                 selector = '[' + attr + '="' + attrValue + '"]';
                 if ( generics[selector] ) {
-                    if ( injectedSelectors[selector] === undefined ) {
+                    if ( injectedSelectors.hasOwnProperty(selector) === false ) {
                         injectedSelectors[selector] = true;
                         out.push(selector);
                     }
                 }
                 selector = node.tagName.toLowerCase() + selector;
                 if ( generics[selector] ) {
-                    if ( injectedSelectors[selector] === undefined ) {
+                    if ( injectedSelectors.hasOwnProperty(selector) === false ) {
                         injectedSelectors[selector] = true;
                         out.push(selector);
                     }
@@ -277,7 +291,7 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
             iSelector = selectors.length;
             while ( iSelector-- ) {
                 selector = selectors[iSelector];
-                if ( injectedSelectors[selector] === undefined ) {
+                if ( injectedSelectors.hasOwnProperty(selector) === false ) {
                     injectedSelectors[selector] = true;
                     out.push(selector);
                 }
@@ -293,7 +307,7 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
 
     var processHighHighGenerics = function() {
         processHighHighGenericsTimer = null;
-        if ( injectedSelectors['{{highHighGenerics}}'] !== undefined ) { return; }
+        if ( injectedSelectors.hasOwnProperty('{{highHighGenerics}}') ) { return; }
         if ( document.querySelector(highGenerics.hideHigh) === null ) { return; }
         injectedSelectors['{{highHighGenerics}}'] = true;
         // We need to filter out possible exception cosmetic filters from
@@ -443,10 +457,10 @@ var messager = vAPI.messaging.channel('contentscript-end.js');
             }
         }
         if ( addedNodeListsTimer === null ) {
-            // I arbitrarily chose 50 ms for now:
+            // I arbitrarily chose 100 ms for now:
             // I have to compromise between the overhead of processing too few
             // nodes too often and the delay of many nodes less often.
-            addedNodeListsTimer = setTimeout(mutationObservedHandler, 75);
+            addedNodeListsTimer = setTimeout(mutationObservedHandler, 100);
         }
     };