Another attempt to fix #5 using @hax's technique.

es-shims · Sep 22, 2011 · 37305bc · 37305bc
1 parent ad15283
commit 37305bc
Showing 1 changed file with 36 additions and 12 deletions.
diff --git a/es5-shim.js b/es5-shim.js
@@ -537,19 +537,37 @@ if (!Object.create) {
 }
 
 // ES5 15.2.3.6
-var oldDefineProperty = Object.defineProperty,
-    defineProperty = oldDefineProperty;
-if (defineProperty) {
-    // detect IE 8's DOM-only implementation of defineProperty;
-    var subject = {};
+
+// Patch for WebKit and IE8 standard mode
+// Designed by hax <hax.github.com>
+// related issue: https://github.com/kriskowal/es5-shim/issues#issue/5
+// IE8 Reference:
+//     http://msdn.microsoft.com/en-us/library/dd282900.aspx
+//     http://msdn.microsoft.com/en-us/library/dd229916.aspx
+// WebKit Bugs:
+//     https://bugs.webkit.org/show_bug.cgi?id=36423
+
+function doesDefinePropertyWork(object) {
     try {
-        Object.defineProperty(subject, "", {});
-        defineProperty = "" in subject;
-    } catch(e) {
-        defineProperty = false;   
+        Object.defineProperty(object, "sentinel", {});
+        return "sentinel" in object;
+    } catch (exception) {
+        // returns falsy
+    }
+}
+
+// check whether defineProperty works if it's given. Otherwise,
+// shim partially.
+if (Object.defineProperty) {
+    var definePropertyWorksOnObject = doesDefinePropertyWork({});
+    var definePropertyWorksOnDom = typeof document == "undefined" ||
+        doesDefinePropertyWork(document.createElement("div"));
+    if (!definePropertyWorksOnObject || !definePropertyWorksOnDom) {
+        var definePropertyFallback = Object.defineProperty;
     }
 }
-if (!defineProperty) {
+
+if (!Object.defineProperty || definePropertyFallback) {
     var ERR_NON_OBJECT_DESCRIPTOR = "Property description must be an object: ";
     var ERR_NON_OBJECT_TARGET = "Object.defineProperty called on non-object: "
     var ERR_ACCESSORS_NOT_SUPPORTED = "getters & setters can not be defined " +
@@ -560,10 +578,16 @@ if (!defineProperty) {
             throw new TypeError(ERR_NON_OBJECT_TARGET + object);
         if ((typeof descriptor != "object" && typeof descriptor != "function") || descriptor === null)
             throw new TypeError(ERR_NON_OBJECT_DESCRIPTOR + descriptor);
+
         // make a valiant attempt to use the real defineProperty
         // for I8's DOM elements.
-        if (oldDefineProperty && object.nodeType)
-            return oldDefineProperty(object, property, descriptor);
+        if (definePropertyFallback) {
+            try {
+                return definePropertyFallback.call(Object, object, property, descriptor);
+            } catch (exception) {
+                // try the shim if the real one doesn't work
+            }
+        }
 
         // If it's a data property.
         if (owns(descriptor, "value")) {