diff --git a/dist/store.common.js b/dist/store.common.js
index f49c149..6575360 100644
--- a/dist/store.common.js
+++ b/dist/store.common.js
@@ -10,7 +10,59 @@
 
 'use strict';
 
-var storage = window.localStorage;
+var storage = window.localStorage,
+    _inMemoryStorage = {},
+    _length = 0; // deal QuotaExceededError if user use incognito mode in browser
+
+(function () {
+  function isSupported() {
+    var _KEY = '_Is_Incognit',
+        _VALUE = 'yes';
+
+    try {
+      storage.setItem(_KEY, _VALUE);
+      storage.removeItem(_KEY);
+      return true;
+    } catch (error) {
+      return false;
+    }
+  }
+
+  if (!isSupported()) {
+    storage.__proto__ = {
+      setItem: function setItem(key, value) {
+        _inMemoryStorage[key] = '' + value;
+
+        if (!_inMemoryStorage.hasOwnProperty(key)) {
+          _length++;
+        }
+      },
+      getItem: function getItem(key) {
+        if (key in _inMemoryStorage) {
+          return _inMemoryStorage[key];
+        }
+
+        return null;
+      },
+      removeItem: function removeItem(key) {
+        if (_inMemoryStorage.hasOwnProperty(key)) {
+          delete _inMemoryStorage[key];
+          _length--;
+        }
+      },
+      clear: function clear() {
+        _inMemoryStorage = {};
+        _length = 0;
+      },
+      length: function length() {
+        return _length;
+      },
+      key: function key(index) {
+        return Object.keys(_inMemoryStorage)[index] || null;
+      }
+    };
+  }
+})();
 
 function isJSON(obj) {
   obj = JSON.stringify(obj);
@@ -44,36 +96,7 @@ function isFunction(value) {
 
 function isArray(value) {
   return Object.prototype.toString.call(value) === "[object Array]";
-} // https://github.com/jaywcjlove/store.js/pull/8
-// Error: QuotaExceededError
-
-
-function dealIncognito(storage) {
-  var _KEY = '_Is_Incognit',
-      _VALUE = 'yes';
-
-  try {
-    storage.setItem(_KEY, _VALUE);
-  } catch (e) {
-    if (e.name === 'QuotaExceededError') {
-      var _nothing = function _nothing() {};
-
-      storage.__proto__ = {
-        setItem: _nothing,
-        getItem: _nothing,
-        removeItem: _nothing,
-        clear: _nothing
-      };
-    }
-  } finally {
-    if (storage.getItem(_KEY) === _VALUE) storage.removeItem(_KEY);
-  }
-
-  return storage;
-} // deal QuotaExceededError if user use incognito mode in browser
-
-
-storage = dealIncognito(storage);
+}
 
 function Store() {
   if (!(this instanceof Store)) {
diff --git a/dist/store.common.min.js b/dist/store.common.min.js
index a51c443..38b07df 100644
--- a/dist/store.common.min.js
+++ b/dist/store.common.min.js
@@ -1,2 +1,2 @@
 /*! storejs v1.0.24 | MIT (c) 2018 kenny wang <wowohoo@qq.com> | https://github.com/jaywcjlove/store.js */
-"use strict";var storage=window.localStorage;function isJSON(t){return t=JSON.stringify(t),/^\{[\s\S]*\}$/.test(t)}function stringify(t){return void 0===t||"function"==typeof t?t+"":JSON.stringify(t)}function deserialize(e){if("string"==typeof e)try{return JSON.parse(e)}catch(t){return e}}function isFunction(t){return"[object Function]"==={}.toString.call(t)}function isArray(t){return"[object Array]"===Object.prototype.toString.call(t)}function dealIncognito(e){var t="_Is_Incognit";try{e.setItem(t,"yes")}catch(t){if("QuotaExceededError"===t.name){var r=function(){};e.__proto__={setItem:r,getItem:r,removeItem:r,clear:r}}}finally{"yes"===e.getItem(t)&&e.removeItem(t)}return e}function Store(){if(!(this instanceof Store))return new Store}storage=dealIncognito(storage),Store.prototype={set:function(t,e){if(t&&!isJSON(t))storage.setItem(t,stringify(e));else if(isJSON(t))for(var r in t)this.set(r,t[r]);return this},get:function(t){if(t)return"?"===t.charAt(0)?this.has(t.substr(1)):deserialize(storage.getItem(t));var r={};return this.forEach(function(t,e){return r[t]=e}),r},clear:function(){return storage.clear(),this},remove:function(t){var e=this.get(t);return storage.removeItem(t),e},has:function(t){return{}.hasOwnProperty.call(this.get(),t)},keys:function(){var e=[];return this.forEach(function(t){e.push(t)}),e},forEach:function(t){for(var e=0,r=storage.length;e<r;e++){var n=storage.key(e);t(n,this.get(n))}return this},search:function(t){for(var e=this.keys(),r={},n=0,o=e.length;n<o;n++)-1<e[n].indexOf(t)&&(r[e[n]]=this.get(e[n]));return r}};var _Store=null;function store(t,e){var r=arguments,n=null;if(_Store||(_Store=Store()),0===r.length)return _Store.get();if(1===r.length){if("string"==typeof t)return _Store.get(t);if(isJSON(t))return _Store.set(t)}if(2===r.length&&"string"==typeof t){if(!e)return _Store.remove(t);if(e&&"string"==typeof e)return _Store.set(t,e);e&&isFunction(e)&&(n=null,n=e(t,_Store.get(t)),store.set(t,n))}if(2===r.length&&isArray(t)&&isFunction(e))for(var o=0,i=t.length;o<i;o++)n=e(t[o],_Store.get(t[o])),store.set(t[o],n);return store}for(var a in Store.prototype)store[a]=Store.prototype[a];module.exports=store;
\ No newline at end of file
+"use strict";var storage=window.localStorage,_inMemoryStorage={},_length=0;function isJSON(t){return t=JSON.stringify(t),/^\{[\s\S]*\}$/.test(t)}function stringify(t){return void 0===t||"function"==typeof t?t+"":JSON.stringify(t)}function deserialize(e){if("string"==typeof e)try{return JSON.parse(e)}catch(t){return e}}function isFunction(t){return"[object Function]"==={}.toString.call(t)}function isArray(t){return"[object Array]"===Object.prototype.toString.call(t)}function Store(){if(!(this instanceof Store))return new Store}(function(){var t="_Is_Incognit";try{return storage.setItem(t,"yes"),storage.removeItem(t),!0}catch(t){return!1}})()||(storage.__proto__={setItem:function(t,e){_inMemoryStorage[t]=""+e,_inMemoryStorage.hasOwnProperty(t)||_length++},getItem:function(t){return t in _inMemoryStorage?_inMemoryStorage[t]:null},removeItem:function(t){_inMemoryStorage.hasOwnProperty(t)&&(delete _inMemoryStorage[t],_length--)},clear:function(){_inMemoryStorage={},_length=0},length:function(){return _length},key:function(t){return Object.keys(_inMemoryStorage)[t]||null}}),Store.prototype={set:function(t,e){if(t&&!isJSON(t))storage.setItem(t,stringify(e));else if(isJSON(t))for(var r in t)this.set(r,t[r]);return this},get:function(t){if(t)return"?"===t.charAt(0)?this.has(t.substr(1)):deserialize(storage.getItem(t));var r={};return this.forEach(function(t,e){return r[t]=e}),r},clear:function(){return storage.clear(),this},remove:function(t){var e=this.get(t);return storage.removeItem(t),e},has:function(t){return{}.hasOwnProperty.call(this.get(),t)},keys:function(){var e=[];return this.forEach(function(t){e.push(t)}),e},forEach:function(t){for(var e=0,r=storage.length;e<r;e++){var n=storage.key(e);t(n,this.get(n))}return this},search:function(t){for(var e=this.keys(),r={},n=0,o=e.length;n<o;n++)-1<e[n].indexOf(t)&&(r[e[n]]=this.get(e[n]));return r}};var _Store=null;function store(t,e){var r=arguments,n=null;if(_Store||(_Store=Store()),0===r.length)return _Store.get();if(1===r.length){if("string"==typeof t)return _Store.get(t);if(isJSON(t))return _Store.set(t)}if(2===r.length&&"string"==typeof t){if(!e)return _Store.remove(t);if(e&&"string"==typeof e)return _Store.set(t,e);e&&isFunction(e)&&(n=null,n=e(t,_Store.get(t)),store.set(t,n))}if(2===r.length&&isArray(t)&&isFunction(e))for(var o=0,i=t.length;o<i;o++)n=e(t[o],_Store.get(t[o])),store.set(t[o],n);return store}for(var a in Store.prototype)store[a]=Store.prototype[a];module.exports=store;
\ No newline at end of file
diff --git a/dist/store.esm.js b/dist/store.esm.js
index 793e42e..7c63956 100644
--- a/dist/store.esm.js
+++ b/dist/store.esm.js
@@ -8,7 +8,59 @@
  * Licensed under the MIT license.
  */
 
-var storage = window.localStorage;
+var storage = window.localStorage,
+    _inMemoryStorage = {},
+    _length = 0; // deal QuotaExceededError if user use incognito mode in browser
+
+(function () {
+  function isSupported() {
+    var _KEY = '_Is_Incognit',
+        _VALUE = 'yes';
+
+    try {
+      storage.setItem(_KEY, _VALUE);
+      storage.removeItem(_KEY);
+      return true;
+    } catch (error) {
+      return false;
+    }
+  }
+
+  if (!isSupported()) {
+    storage.__proto__ = {
+      setItem: function setItem(key, value) {
+        _inMemoryStorage[key] = '' + value;
+
+        if (!_inMemoryStorage.hasOwnProperty(key)) {
+          _length++;
+        }
+      },
+      getItem: function getItem(key) {
+        if (key in _inMemoryStorage) {
+          return _inMemoryStorage[key];
+        }
+
+        return null;
+      },
+      removeItem: function removeItem(key) {
+        if (_inMemoryStorage.hasOwnProperty(key)) {
+          delete _inMemoryStorage[key];
+          _length--;
+        }
+      },
+      clear: function clear() {
+        _inMemoryStorage = {};
+        _length = 0;
+      },
+      length: function length() {
+        return _length;
+      },
+      key: function key(index) {
+        return Object.keys(_inMemoryStorage)[index] || null;
+      }
+    };
+  }
+})();
 
 function isJSON(obj) {
   obj = JSON.stringify(obj);
@@ -42,36 +94,7 @@ function isFunction(value) {
 
 function isArray(value) {
   return Object.prototype.toString.call(value) === "[object Array]";
-} // https://github.com/jaywcjlove/store.js/pull/8
-// Error: QuotaExceededError
-
-
-function dealIncognito(storage) {
-  var _KEY = '_Is_Incognit',
-      _VALUE = 'yes';
-
-  try {
-    storage.setItem(_KEY, _VALUE);
-  } catch (e) {
-    if (e.name === 'QuotaExceededError') {
-      var _nothing = function _nothing() {};
-
-      storage.__proto__ = {
-        setItem: _nothing,
-        getItem: _nothing,
-        removeItem: _nothing,
-        clear: _nothing
-      };
-    }
-  } finally {
-    if (storage.getItem(_KEY) === _VALUE) storage.removeItem(_KEY);
-  }
-
-  return storage;
-} // deal QuotaExceededError if user use incognito mode in browser
-
-
-storage = dealIncognito(storage);
+}
 
 function Store() {
   if (!(this instanceof Store)) {
diff --git a/dist/store.js b/dist/store.js
index 414443b..60701ad 100644
--- a/dist/store.js
+++ b/dist/store.js
@@ -14,7 +14,59 @@
   (global.store = factory());
 }(this, (function () { 'use strict';
 
-  var storage = window.localStorage;
+  var storage = window.localStorage,
+      _inMemoryStorage = {},
+      _length = 0; // deal QuotaExceededError if user use incognito mode in browser
+
+  (function () {
+    function isSupported() {
+      var _KEY = '_Is_Incognit',
+          _VALUE = 'yes';
+
+      try {
+        storage.setItem(_KEY, _VALUE);
+        storage.removeItem(_KEY);
+        return true;
+      } catch (error) {
+        return false;
+      }
+    }
+
+    if (!isSupported()) {
+      storage.__proto__ = {
+        setItem: function setItem(key, value) {
+          _inMemoryStorage[key] = '' + value;
+
+          if (!_inMemoryStorage.hasOwnProperty(key)) {
+            _length++;
+          }
+        },
+        getItem: function getItem(key) {
+          if (key in _inMemoryStorage) {
+            return _inMemoryStorage[key];
+          }
+
+          return null;
+        },
+        removeItem: function removeItem(key) {
+          if (_inMemoryStorage.hasOwnProperty(key)) {
+            delete _inMemoryStorage[key];
+            _length--;
+          }
+        },
+        clear: function clear() {
+          _inMemoryStorage = {};
+          _length = 0;
+        },
+        length: function length() {
+          return _length;
+        },
+        key: function key(index) {
+          return Object.keys(_inMemoryStorage)[index] || null;
+        }
+      };
+    }
+  })();
 
   function isJSON(obj) {
     obj = JSON.stringify(obj);
@@ -48,36 +100,7 @@
 
   function isArray(value) {
     return Object.prototype.toString.call(value) === "[object Array]";
-  } // https://github.com/jaywcjlove/store.js/pull/8
-  // Error: QuotaExceededError
-
-
-  function dealIncognito(storage) {
-    var _KEY = '_Is_Incognit',
-        _VALUE = 'yes';
-
-    try {
-      storage.setItem(_KEY, _VALUE);
-    } catch (e) {
-      if (e.name === 'QuotaExceededError') {
-        var _nothing = function _nothing() {};
-
-        storage.__proto__ = {
-          setItem: _nothing,
-          getItem: _nothing,
-          removeItem: _nothing,
-          clear: _nothing
-        };
-      }
-    } finally {
-      if (storage.getItem(_KEY) === _VALUE) storage.removeItem(_KEY);
-    }
-
-    return storage;
-  } // deal QuotaExceededError if user use incognito mode in browser
-
-
-  storage = dealIncognito(storage);
+  }
 
   function Store() {
     if (!(this instanceof Store)) {
diff --git a/dist/store.min.js b/dist/store.min.js
index 7daaebb..853b789 100644
--- a/dist/store.min.js
+++ b/dist/store.min.js
@@ -1,2 +1,2 @@
 /*! storejs v1.0.24 | MIT (c) 2018 kenny wang <wowohoo@qq.com> | https://github.com/jaywcjlove/store.js */
-!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):t.store=e()}(this,function(){"use strict";var i=window.localStorage;function f(t){return t=JSON.stringify(t),/^\{[\s\S]*\}$/.test(t)}function u(t){return"[object Function]"==={}.toString.call(t)}function s(){if(!(this instanceof s))return new s}i=function(e){var t="_Is_Incognit";try{e.setItem(t,"yes")}catch(t){if("QuotaExceededError"===t.name){var r=function(){};e.__proto__={setItem:r,getItem:r,removeItem:r,clear:r}}}finally{"yes"===e.getItem(t)&&e.removeItem(t)}return e}(i),s.prototype={set:function(t,e){if(t&&!f(t))i.setItem(t,void 0===(n=e)||"function"==typeof n?n+"":JSON.stringify(n));else if(f(t))for(var r in t)this.set(r,t[r]);var n;return this},get:function(t){if(t)return"?"===t.charAt(0)?this.has(t.substr(1)):function(e){if("string"==typeof e)try{return JSON.parse(e)}catch(t){return e}}(i.getItem(t));var r={};return this.forEach(function(t,e){return r[t]=e}),r},clear:function(){return i.clear(),this},remove:function(t){var e=this.get(t);return i.removeItem(t),e},has:function(t){return{}.hasOwnProperty.call(this.get(),t)},keys:function(){var e=[];return this.forEach(function(t){e.push(t)}),e},forEach:function(t){for(var e=0,r=i.length;e<r;e++){var n=i.key(e);t(n,this.get(n))}return this},search:function(t){for(var e=this.keys(),r={},n=0,i=e.length;n<i;n++)-1<e[n].indexOf(t)&&(r[e[n]]=this.get(e[n]));return r}};var c=null;function a(t,e){var r=arguments,n=null;if(c||(c=s()),0===r.length)return c.get();if(1===r.length){if("string"==typeof t)return c.get(t);if(f(t))return c.set(t)}if(2===r.length&&"string"==typeof t){if(!e)return c.remove(t);if(e&&"string"==typeof e)return c.set(t,e);e&&u(e)&&(n=null,n=e(t,c.get(t)),a.set(t,n))}if(2===r.length&&"[object Array]"===Object.prototype.toString.call(t)&&u(e))for(var i=0,o=t.length;i<o;i++)n=e(t[i],c.get(t[i])),a.set(t[i],n);return a}for(var t in s.prototype)a[t]=s.prototype[t];return a});
\ No newline at end of file
+!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):t.store=e()}(this,function(){"use strict";var i=window.localStorage,n={},r=0;function u(t){return t=JSON.stringify(t),/^\{[\s\S]*\}$/.test(t)}function f(t){return"[object Function]"==={}.toString.call(t)}function s(){if(!(this instanceof s))return new s}(function(){var t="_Is_Incognit";try{return i.setItem(t,"yes"),i.removeItem(t),!0}catch(t){return!1}})()||(i.__proto__={setItem:function(t,e){n[t]=""+e,n.hasOwnProperty(t)||r++},getItem:function(t){return t in n?n[t]:null},removeItem:function(t){n.hasOwnProperty(t)&&(delete n[t],r--)},clear:function(){n={},r=0},length:function(){return r},key:function(t){return Object.keys(n)[t]||null}}),s.prototype={set:function(t,e){if(t&&!u(t))i.setItem(t,void 0===(r=e)||"function"==typeof r?r+"":JSON.stringify(r));else if(u(t))for(var n in t)this.set(n,t[n]);var r;return this},get:function(t){if(t)return"?"===t.charAt(0)?this.has(t.substr(1)):function(e){if("string"==typeof e)try{return JSON.parse(e)}catch(t){return e}}(i.getItem(t));var n={};return this.forEach(function(t,e){return n[t]=e}),n},clear:function(){return i.clear(),this},remove:function(t){var e=this.get(t);return i.removeItem(t),e},has:function(t){return{}.hasOwnProperty.call(this.get(),t)},keys:function(){var e=[];return this.forEach(function(t){e.push(t)}),e},forEach:function(t){for(var e=0,n=i.length;e<n;e++){var r=i.key(e);t(r,this.get(r))}return this},search:function(t){for(var e=this.keys(),n={},r=0,i=e.length;r<i;r++)-1<e[r].indexOf(t)&&(n[e[r]]=this.get(e[r]));return n}};var c=null;function a(t,e){var n=arguments,r=null;if(c||(c=s()),0===n.length)return c.get();if(1===n.length){if("string"==typeof t)return c.get(t);if(u(t))return c.set(t)}if(2===n.length&&"string"==typeof t){if(!e)return c.remove(t);if(e&&"string"==typeof e)return c.set(t,e);e&&f(e)&&(r=null,r=e(t,c.get(t)),a.set(t,r))}if(2===n.length&&"[object Array]"===Object.prototype.toString.call(t)&&f(e))for(var i=0,o=t.length;i<o;i++)r=e(t[i],c.get(t[i])),a.set(t[i],r);return a}for(var t in s.prototype)a[t]=s.prototype[t];return a});
\ No newline at end of file
diff --git a/lib/main.js b/lib/main.js
index 2e6d918..3b1e924 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -1,4 +1,51 @@
-var storage = window.localStorage;
+var storage = window.localStorage, _inMemoryStorage = {}, _length = 0;
+
+// deal QuotaExceededError if user use incognito mode in browser
+(function(){
+  function isSupported(){
+    var _KEY = '_Is_Incognit', _VALUE = 'yes';
+    try {
+      storage.setItem(_KEY, _VALUE);
+      storage.removeItem(_KEY);
+      return true
+    } catch (error) {
+      return false;      
+    }
+  }
+
+  if(!isSupported()){
+    storage.__proto__ = {
+      setItem: function (key, value){
+        _inMemoryStorage[key] = '' + value;
+        if(!_inMemoryStorage.hasOwnProperty(key)){
+          _length++;
+        }
+      },
+      getItem: function (key){
+        if(key in _inMemoryStorage){
+          return _inMemoryStorage[key];
+        }
+        return null;
+      },
+      removeItem: function (key){
+        if(_inMemoryStorage.hasOwnProperty(key)){
+          delete _inMemoryStorage[key];
+          _length--;
+        }
+      },
+      clear: function () {
+        _inMemoryStorage = {};
+        _length = 0;
+      },
+      length: function (){
+        return _length;
+      },
+      key: function (index){
+        return Object.keys(_inMemoryStorage)[index] || null;
+      }
+    }
+  }
+})()
 
 function isJSON(obj) {
   obj = JSON.stringify(obj);
@@ -18,23 +65,6 @@ function deserialize(value) {
 }
 function isFunction(value) { return ({}).toString.call(value) === "[object Function]"; }
 function isArray(value) { return Object.prototype.toString.call(value) === "[object Array]"; }
-// https://github.com/jaywcjlove/store.js/pull/8
-// Error: QuotaExceededError
-function dealIncognito(storage) {
-  var _KEY = '_Is_Incognit', _VALUE = 'yes';
-  try { storage.setItem(_KEY, _VALUE) }
-  catch (e) {
-    if (e.name === 'QuotaExceededError') {
-      var _nothing = function () { };
-      storage.__proto__ = { setItem: _nothing, getItem: _nothing, removeItem: _nothing, clear: _nothing };
-    }
-  }
-  finally { if (storage.getItem(_KEY) === _VALUE) storage.removeItem(_KEY); }
-  return storage;
-}
-
-// deal QuotaExceededError if user use incognito mode in browser
-storage = dealIncognito(storage);
 
 function Store() {
   if (!(this instanceof Store)) {