diff --git a/src/chatwork.js b/src/chatwork.js
index 56fc928..5410943 100644
--- a/src/chatwork.js
+++ b/src/chatwork.js
@@ -1,5 +1,5 @@
 /*!
- * ChatWork - JavaScript SDK for ChatWork API v1 Preview
+ * ChatWork - Chrome JavaScript SDK for ChatWork API v1 Preview
  *
  * Copyright 2013, Tetsuwo OISHI.
  * Dual license under the MIT license.
@@ -13,8 +13,14 @@ function ChatWork(param) {
     this.initialize.apply(this, arguments);
 }
 
+/**
+ * Initialize
+ *
+ * @param {object} param
+ */
 ChatWork.prototype.initialize = function(param) {
     this.apiBaseUrl = 'https://api.chatwork.com/v1';
+    this.url        = 'https://chatwork.com';
     this.name       = '_chatwork';
     this.times      = 0;
     this.requests   = [];
@@ -35,24 +41,38 @@ ChatWork.prototype.initialize = function(param) {
         }
     }
 
-    this.output(param);
+    this.log(param);
 };
 
-ChatWork.prototype.setApiToken = function(val) {
-    this.config.apiToken = val;
+/**
+ * Set API Token
+ *
+ * @param {string} apiToken
+ */
+ChatWork.prototype.setApiToken = function(apiToken) {
+    this.config.apiToken = apiToken;
     return this;
 };
 
-ChatWork.prototype.output = function(val) {
+/**
+ * Logging
+ *
+ */
+ChatWork.prototype.log = function() {
     if (this.debug) {
-        console.log(val);
+        console.log(arguments);
     }
 };
 
+/**
+ * Serialize parameters
+ *
+ * @param {object} param
+ * @param {string} prefix
+ */
 ChatWork.prototype.serialize = function(param, prefix) {
     var query = [];
-
-    for(var p in param) {
+    for (var p in param) {
         var k = prefix ? prefix + '[' + p + ']' : p, v = param[p];
         query.push(
             typeof v == 'object' ?
@@ -60,43 +80,31 @@ ChatWork.prototype.serialize = function(param, prefix) {
                 encodeURIComponent(k) + '=' + encodeURIComponent(v)
         );
     }
-
     return query.join('&');
 };
 
+/**
+ * API Caller
+ *
+ * @param {string} method
+ * @param {object} param
+ * @param {function} callback
+ */
 ChatWork.prototype.api = function(method, param, callback) {
-    var callbackName = this.name + '_cb_' + this.times;
-    this.win[callbackName] = callback;
-
-    param = param || {};
-    param.api_key = this.config.apiKey;
-    param.jsonp   = callbackName;
-
-    this.requests[this.times] = {
-        method: method,
-        param: param,
-        callback: callback,
-        callbackName: callbackName
-    };
-
-    if (param.limit === 'all') {
-        param.limit = null;
+    var endpoint = this.apiBaseUrl + method;
+    try {
+        var xhr = new XMLHttpRequest();
+        xhr.onreadystatechange = function() {
+            if (xhr.readyState == 4 && xhr.status == 200) {
+                var response = JSON.parse(xhr.responseText);
+                callback(response);
+            }
+        };
+        xhr.open('GET', endpoint);
+        xhr.setRequestHeader('X-ChatWorkToken', this.config.apiToken);
+        xhr.send();
+    } catch (ex) {
+        this.log('xhr.exception', ex);
     }
-
-    this.times++;
-
-    (function(that, d, t) {
-        var e = d.createElement(t);
-        e.type = 'text/javascript';
-        e.async = true;
-        e.src = that.apiUrl;
-        e.src += method;
-        e.src += '?' + that.serialize(param);
-        that.output(e.src);
-        var s = d.getElementsByTagName(t)[0];
-        s.parentNode.insertBefore(e, s);
-    })(this, document, 'script');
-
     return this;
 };
-