Selector: Make empty attribute selectors work in IE again

qSA in IE 11/Edge often (but not always) don't find elements with an empty
name attribute selector (`[name=""]`). Detect that & fall back to Sizzle
traversal.

Interestingly, IE 10 & older don't seem to have the issue.

Fixes gh-4435
Closes gh-4510

3 files changed, 18 insertions, 4 deletions

diff --git a/src/selector.js b/src/selector.js
index 019f25d62..66abe7935 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -5,6 +5,7 @@ import documentElement from "./var/documentElement.js";
 import indexOf from "./var/indexOf.js";
 import pop from "./var/pop.js";
 import push from "./var/push.js";
+import whitespace from "./selector/var/whitespace.js";
 import rbuggyQSA from "./selector/rbuggyQSA.js";
 import support from "./selector/support.js";
 
@@ -41,9 +42,6 @@ var i,
 
 	// Regular expressions
 
-	// https://www.w3.org/TR/css3-selectors/#whitespace
-	whitespace = "[\\x20\\t\\r\\n\\f]",
-
 	// https://www.w3.org/TR/css-syntax-3/#ident-token-diagram
 	identifier = "(?:\\\\[\\da-fA-F]{1,6}" + whitespace +
 		"?|\\\\[^\\r\\n\\f]|[\\w-]|[^\0-\\x7f])+",
diff --git a/src/selector/rbuggyQSA.js b/src/selector/rbuggyQSA.js
index f638fc429..2c853a0f1 100644
--- a/src/selector/rbuggyQSA.js
+++ b/src/selector/rbuggyQSA.js
@@ -1,8 +1,10 @@
 import document from "../var/document.js";
 import isIE from "../var/isIE.js";
+import whitespace from "./var/whitespace.js";
 
 var rbuggyQSA = [],
-	testEl = document.createElement( "div" );
+	testEl = document.createElement( "div" ),
+	input = document.createElement( "input" );
 
 testEl.innerHTML = "<a href=''></a>";
 
@@ -19,6 +21,18 @@ if ( isIE ) {
 	rbuggyQSA.push( ":enabled", ":disabled" );
 }
 
+// Support: IE 11+, Edge 15 - 18+
+// IE 11/Edge don't find elements on a `[name='']` query in some cases.
+// Adding a temporary attribute to the document before the selection works
+// around the issue.
+// Interestingly, IE 10 & older don't seem to have the issue.
+input.setAttribute( "name", "" );
+testEl.appendChild( input );
+if ( !testEl.querySelectorAll( "[name='']" ).length ) {
+	rbuggyQSA.push( "\\[" + whitespace + "*name" + whitespace + "*=" +
+		whitespace + "*(?:''|\"\")" );
+}
+
 rbuggyQSA = rbuggyQSA.length && new RegExp( rbuggyQSA.join( "|" ) );
 
 export default rbuggyQSA;
diff --git a/src/selector/var/whitespace.js b/src/selector/var/whitespace.js
new file mode 100644
index 000000000..dcac814c7
--- /dev/null
+++ b/src/selector/var/whitespace.js
@@ -0,0 +1,2 @@
+// https://www.w3.org/TR/css3-selectors/#whitespace
+export default "[\\x20\\t\\r\\n\\f]";