diff --git a/unpacked/extensions/CHTML-preview.js b/unpacked/extensions/CHTML-preview.js
new file mode 100644
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+++ b/unpacked/extensions/CHTML-preview.js
@@ -0,0 +1,107 @@
+/* -*- Mode: Javascript; indent-tabs-mode:nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+
+/*************************************************************
+ *
+ *  MathJax/extensions/CHTML-preview.js
+ *  
+ *  Implements a fast preview using the Common-HTML output jax
+ *  and then a slower update to the more accurate HTML-CSS output
+ *  (or whatever the user has selected).
+ *  
+ *  ---------------------------------------------------------------------
+ *  
+ *  Copyright (c) 2014 The MathJax Consortium
+ * 
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+(function (HUB,HTML) {
+
+  var CHTMLpreview = MathJax.Extension["CHTML-preview"] = {
+    version: "1.0",
+
+    //
+    //  Configuration for the chinking of the main output
+    //  after the previews have been created
+    //
+    config: HUB.CombineConfig("CHTML-preview",{
+      EqnChunk: 5, EqnChunkFactor: 1, EqnChunkDelay: 100
+    }),
+
+    //
+    //  Ajust the chunking of the output jax
+    //
+    Config: function () {
+      var config = this.config;
+      HUB.Config({
+        "HTML-CSS": {
+          EqnChunk: config.EqnChunk,
+          EqnChunkFactor: config.EqnChunkFactor,
+          EqnChunkDelay: config.EqnChunkDelay
+        },
+        "SVG": {
+          EqnChunk: config.EqnChunk,
+          EqnChunkFactor: config.EqnChunkFactor,
+          EqnChunkDelay: config.EqnChunkDelay
+        }
+      });
+    },
+
+    //
+    //  Insert a preview span, if there isn't one already,
+    //  and call the CommonHTML output jax to create the preview
+    //
+    Preview: function (data) {
+      var preview = data.script.previousSibling;
+      if (!preview || preview.className !== MathJax.Hub.config.preRemoveClass) {
+        preview = HTML.Element("span",{className:MathJax.Hub.config.preRemoveClass});
+        data.script.parentNode.insertBefore(preview,data.script);
+      }
+      preview.innerHTML = "";
+      data.math.root.toCommonHTML(preview);
+      return data;
+    },
+
+    //
+    //  Hook into the inut jax postFilter to create the previews as
+    //  the input jax are processed.
+    //
+    Register: function (name) {
+      HUB.Register.StartupHook(name+" Jax Require",function () {
+        var jax = MathJax.InputJax[name];
+        var delay = HUB.config.delayJaxRegistration;
+        HUB.config.delayJaxRegistration = true;
+        HUB.Register.StartupHook(name+" Jax Ready",function () {HUB.config.delayJaxRegistration = delay});
+        jax.require.push(
+          "[MathJax]/jax/output/CommonHTML/config.js",
+          "[MathJax]/jax/output/CommonHTML/jax.js"
+        );
+        jax.postfilterHooks.Add(["Preview",MathJax.Extension["CHTML-preview"]]);
+      });
+    }
+  }
+
+  //
+  //  Hook into each input jax
+  //
+  CHTMLpreview.Register("TeX");
+  CHTMLpreview.Register("MathML");
+  CHTMLpreview.Register("AsciiMath");
+  
+  HUB.Register.StartupHook("End Config",["Config",CHTMLpreview]);
+
+})(MathJax.Hub,MathJax.HTML);
+
+MathJax.Ajax.loadComplete("[MathJax]/extensions/CHTML-preview.js");
+