Selector: Use shallow document comparisons to avoid IE/Edge crashes

IE/Edge sometimes crash when comparing documents between frames using the strict equality operator (`===` & `!==`). Funnily enough, shallow comparisons (`==` & `!=`) work without crashing. Fixes gh-4441 Closes gh-4471
jquery · Sep 24, 2019 · aa6344b · aa6344b
1 parent b59107f
commit aa6344b
Showing 1 changed file with 24 additions and 13 deletions.
diff --git a/src/selector.js b/src/selector.js
@@ -172,10 +172,7 @@ function find( selector, context, results, seed ) {
 
  // Try to shortcut find operations (as opposed to filters) in HTML documents
  if ( !seed ) {
-
- if ( ( context ? context.ownerDocument || context : preferredDoc ) !== document ) {
- setDocument( context );
- }
+ setDocument( context );
  context = context || document;
 
  if ( documentIsHTML ) {
@@ -425,7 +422,11 @@ function setDocument( node ) {
  doc = node ? node.ownerDocument || node : preferredDoc;
 
  // Return early if doc is invalid or already selected
- if ( doc === document || doc.nodeType !== 9 ) {
+ // Support: IE 11+, Edge 17 - 18+
+ // IE/Edge sometimes throw a "Permission denied" error when strict-comparing
+ // two documents; shallow comparisons work.
+ // eslint-disable-next-line eqeqeq
+ if ( doc == document || doc.nodeType !== 9 ) {
  return;
  }
 
@@ -436,7 +437,11 @@ function setDocument( node ) {
 
  // Support: IE 9 - 11+, Edge 12 - 18+
  // Accessing iframe documents after unload throws "permission denied" errors (jQuery #13936)
- if ( preferredDoc !== document &&
+ // Support: IE 11+, Edge 17 - 18+
+ // IE/Edge sometimes throw a "Permission denied" error when strict-comparing
+ // two documents; shallow comparisons work.
+ // eslint-disable-next-line eqeqeq
+ if ( preferredDoc != document &&
  ( subWindow = document.defaultView ) && subWindow.top !== subWindow ) {
 
  // Support: IE 9 - 11+, Edge 12 - 18+
@@ -449,11 +454,7 @@ find.matches = function( expr, elements ) {
 };
 
 find.matchesSelector = function( elem, expr ) {
-
- // Set document vars if needed
- if ( ( elem.ownerDocument || elem ) !== document ) {
- setDocument( elem );
- }
+ setDocument( elem );
 
  if ( documentIsHTML &&
  !nonnativeSelectorCache[ expr + " " ] &&
@@ -1413,14 +1414,24 @@ function matcherFromGroupMatchers( elementMatchers, setMatchers ) {
  dirrunsUnique = ( dirruns += contextBackup == null ? 1 : Math.random() || 0.1 );
 
  if ( outermost ) {
- outermostContext = context === document || context || outermost;
+
+ // Support: IE 11+, Edge 17 - 18+
+ // IE/Edge sometimes throw a "Permission denied" error when strict-comparing
+ // two documents; shallow comparisons work.
+ // eslint-disable-next-line eqeqeq
+ outermostContext = context == document || context || outermost;
  }
 
  // Add elements passing elementMatchers directly to results
  for ( ; ( elem = elems[ i ] ) != null; i++ ) {
  if ( byElement && elem ) {
  j = 0;
- if ( !context && elem.ownerDocument !== document ) {
+
+ // Support: IE 11+, Edge 17 - 18+
+ // IE/Edge sometimes throw a "Permission denied" error when strict-comparing
+ // two documents; shallow comparisons work.
+ // eslint-disable-next-line eqeqeq
+ if ( !context && elem.ownerDocument != document ) {
  setDocument( elem );
  xml = !documentIsHTML;
  }