diff --git a/docinfo.html b/docinfo.html
index f724f46b6..5a27d44c2 100644
--- a/docinfo.html
+++ b/docinfo.html
@@ -1,10 +1,9 @@
+<script type="text/javascript" src="public/js/google-analytics.js"></script>
 <link rel="canonical" href="http://azu.github.io/promises-book/">
 <link href="public/img/favicon.ico" rel="shortcut icon" type="image/x-icon">
 <link rel="icon" sizes="16x16 32x32" href="public/img/favicon.ico">
 <link rel="stylesheet" type="text/css" href="public/css/overload.css"/>
-<script type="text/javascript" src="public/js/sync-toc.js"></script>
-<script type="text/javascript" src="public/js/google-analytics.js"></script>
-<script type="text/javascript" src="public/js/bug-report.js"></script>
-<link rel="stylesheet" type="text/css" href="node_modules/codemirror-console-ui/components/mirror-console-compoenent.css"/>
+<link rel="stylesheet" type="text/css"
+      href="node_modules/codemirror-console-ui/components/mirror-console-compoenent.css"/>
 <link rel="stylesheet" type="text/css" href="node_modules/codemirror/lib/codemirror.css">
-<script type="text/javascript" src="public/js/app.js"></script>
+<script type="text/javascript" src="public/js/app.js" async defer></script>
diff --git a/gulpfile.js b/gulpfile.js
index 4ee4ac5c1..a19b1901c 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -4,6 +4,9 @@ var path = require("path");
 var rename = require("gulp-rename");
 var inlining = require("gulp-inlining-node-require");
 var removeUseString = require("gulp-remove-use-strict");
+gulp.task("build-js", function () {
+
+});
 gulp.task("embed", function () {
     return gulp.src(["./Ch*/src/**/*.js", "./Ch*/lib/*.js", "./Ch3_Testing/test/*.js"], {base: './'})
         .pipe(inlining())
diff --git a/public/js/bug-report.js b/public/js/bug-report.js
index c8a14d8c1..9eb99ada4 100644
--- a/public/js/bug-report.js
+++ b/public/js/bug-report.js
@@ -1,4 +1,11 @@
 "use strict";
+var TOCHighlighter = require("./sync-toc");
+function quoteText(text) {
+    return text.split("\n").map(function (line) {
+        return "> " + line;
+    }).join("\n");
+}
+
 function BugReporter() {
     var highLightLevel = ["h1", "h2", "h3"];
     var sections = document.querySelectorAll(".sect2");
@@ -36,14 +43,8 @@ BugReporter.prototype.report = function () {
         + "&labels=" + encodeURIComponent(this.github_issue_labels);
     window.open(url, "_blank");
 };
-window.addEventListener("load", function (event) {
-
-    function quoteText(text) {
-        return text.split("\n").map(function (line) {
-            return "> " + line;
-        }).join("\n");
-    }
-
+module.exports = BugReporter;
+module.exports.initilize = function () {
     var reportElement = document.createElement("button");
     reportElement.textContent = "バグ報告";
     reportElement.setAttribute("style", "position:fixed; right:0;bottom:0;");
@@ -59,5 +60,4 @@ window.addEventListener("load", function (event) {
         bug.report();
     });
     document.body.appendChild(reportElement);
-});
-
+};
\ No newline at end of file
diff --git a/public/js/editor.js b/public/js/editor.js
new file mode 100644
index 000000000..48e224ffb
--- /dev/null
+++ b/public/js/editor.js
@@ -0,0 +1,16 @@
+/**
+ * Created by azu on 2014/06/11.
+ * LICENSE : MIT
+ */
+"use strict";
+module.exports.initilize = function () {
+    var consoleUI = require("codemirror-console-ui");
+    var codeBlocks = document.querySelectorAll("div.listingblock");
+    for (var i = 0; i < codeBlocks.length; i++) {
+        var codeBlock = codeBlocks[i];
+        var code = codeBlock.getElementsByTagName("code")[0];
+        if (code) {
+            consoleUI(codeBlock, code.textContent);
+        }
+    }
+}
\ No newline at end of file
diff --git a/public/js/index.js b/public/js/index.js
index 7058ce183..d7ea76b3a 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -4,14 +4,8 @@
  */
 "use strict";
 function windowOnload() {
-    var consoleUI = require("codemirror-console-ui");
-    var codeBlocks = document.querySelectorAll("div.listingblock");
-    for (var i = 0; i < codeBlocks.length; i++) {
-        var codeBlock = codeBlocks[i];
-        var code = codeBlock.getElementsByTagName("code")[0];
-        if (code) {
-            consoleUI(codeBlock, code.textContent);
-        }
-    }
+    require("./editor").initilize();
+    require("./sync-toc").initilize();
+    require("./bug-report").initilize();
 }
 window.addEventListener("load", windowOnload);
\ No newline at end of file
diff --git a/public/js/sync-toc.js b/public/js/sync-toc.js
index d97c83a22..7e211cac6 100644
--- a/public/js/sync-toc.js
+++ b/public/js/sync-toc.js
@@ -60,7 +60,8 @@ TOCHighlighter.prototype.findAllChildHeader = function (parent) {
     }
     return [];
 };
-window.addEventListener("load", function onLoad() {
+module.exports = TOCHighlighter;
+module.exports.initilize = function initilize() {
     var highLightLevel = ["h1", "h2", "h3"];
     var chapters = document.querySelectorAll(".sect1");
     var sections = document.querySelectorAll(".sect2");
@@ -78,4 +79,4 @@ window.addEventListener("load", function onLoad() {
     }
 
     window.addEventListener("scroll", onScroll);
-});
+};