Selector: Wrap activeElement access in try-catch

mgol · web-flow · commit 3936cf3ef355 · 2023-03-27T21:48:38.000+02:00
In IE 9 accessing `document.activeElement` may throw; see https://bugs.jquery.com/ticket/13393. We've already guarded against this in event code but not in selector. Closes gh-5229
diff --git a/src/selector.js b/src/selector.js
@@ -163,6 +163,17 @@ var i,
 		{ dir: "parentNode", next: "legend" }
 	);
 
+// Support: IE <=9 only
+// Accessing document.activeElement can throw unexpectedly
+// https://bugs.jquery.com/ticket/13393
+// An identical function exists in `src/event.js` but they use different
+// `documents` so it cannot be easily extracted.
+function safeActiveElement() {
+	try {
+		return document.activeElement;
+	} catch ( err ) { }
+}
+
 // Optimize for push.apply( _, NodeList )
 try {
 	push.apply(
@@ -1316,7 +1327,7 @@ Expr = jQuery.expr = {
 		},
 
 		focus: function( elem ) {
-			return elem === document.activeElement &&
+			return elem === safeActiveElement() &&
 				document.hasFocus() &&
 				!!( elem.type || elem.href || ~elem.tabIndex );
 		},
