simulate object.create via ActiveXObject under IE8 zloirock#727

packages/core-js/internals/object-create.js

@@ -8,16 +8,33 @@ var sharedKey = require('../internals/shared-key');
 
 var IE_PROTO = sharedKey('IE_PROTO');
 var PROTOTYPE = 'prototype';
+var SCRIPT = 'script';
 var EmptyConstructor = function () { /* empty */ };
+var scriptTag = function (content) {
+  var GT = '>';
+  var LT = '<';
+  return LT + SCRIPT + GT + content + LT + '/' + SCRIPT + GT;
+};
+
+var NullProtoObject = function (ProtoObject) {
+  var length = enumBugKeys.length;
+  while (length--) delete ProtoObject[PROTOTYPE][enumBugKeys[length]];
+  return ProtoObject;
+};
+
+// Create object with fake `null` prototype: use ActiveX Object with cleared prototype
+var NullProtoObjectViaActiveX = function (activeXDocument) {
+  activeXDocument.write(scriptTag(''));
+  activeXDocument.close();
+  var temp = activeXDocument.parentWindow.Object;
+  activeXDocument = null; // avoid memory leak
+  return NullProtoObject(temp);
+};
 
 // Create object with fake `null` prototype: use iframe Object with cleared prototype
-var NullProtoObject = function () {
+var NullProtoObjectViaIFrame = function () {
   // Thrash, waste and sodomy: IE GC bug
   var iframe = documentCreateElement('iframe');
-  var length = enumBugKeys.length;
-  var GT = '>';
-  var LT = '<';
-  var SCRIPT = 'script';
   var JS = 'java' + SCRIPT + ':';
   var iframeDocument;
   iframe.style.display = 'none';
@@ -26,11 +43,9 @@ var NullProtoObject = function () {
   iframe.src = String(JS);
   iframeDocument = iframe.contentWindow.document;
   iframeDocument.open();
-  iframeDocument.write(LT + SCRIPT + GT + 'document.F=Object' + LT + '/' + SCRIPT + GT);
+  iframeDocument.write(scriptTag('document.F=Object'));
   iframeDocument.close();
-  NullProtoObject = iframeDocument.F;
-  while (length--) delete NullProtoObject[PROTOTYPE][enumBugKeys[length]];
-  return NullProtoObject();
+  return NullProtoObject(iframeDocument.F);
 };
 
 hiddenKeys[IE_PROTO] = true;
@@ -45,6 +60,18 @@ module.exports = Object.create || function create(O, Properties) {
     EmptyConstructor[PROTOTYPE] = null;
     // add "__proto__" for Object.getPrototypeOf polyfill
     result[IE_PROTO] = O;
-  } else result = NullProtoObject();
+  } else {
+    // Check for document.domain and active x support
+    // No need to use active x approach when document.domain is not set
+    // see https://github.com/es-shims/es5-shim/issues/150
+    // variation of https://github.com/kitcambridge/es5-shim/commit/4f738ac066346
+    var activeXDocument;
+    try {
+      /* global ActiveXObject */
+      activeXDocument = document.domain && new ActiveXObject('htmlfile');
+    } catch (error) { /* ignore */ }
+
+    result = activeXDocument ? NullProtoObjectViaActiveX(activeXDocument) : NullProtoObjectViaIFrame();
+  }
   return Properties === undefined ? result : defineProperties(result, Properties);
 };