diff --git a/README.md b/README.md
index 230cd3c4d..9b8be7563 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@
 - [Documentation](http://vuejs.github.io/vuex/)
 - [Great introduction and explanation by @skyronic](http://skyronic.com/2016/01/03/vuex-basics-tutorial/) (using outdated 0.3.0 API, but still worth a read!)
 - [Vuex introduction video - James Browne from London Vue.js Meetup #1](https://www.youtube.com/watch?v=l1KHL-TX3qs)
+- [Feathers.js example using Vue.js and Vuex on the client to maintain state](https://github.com/niallobrien/feathers-chat-example) by [Niall O'Brien](https://github.com/niallobrien) (Twitter: [@niall_obrien](https://twitter.com/niall_obrien))
 
 ## Examples
 
diff --git a/docs/en/actions.md b/docs/en/actions.md
index dc9efd402..3bb36bfb3 100644
--- a/docs/en/actions.md
+++ b/docs/en/actions.md
@@ -10,7 +10,7 @@ function increment (store) {
   store.dispatch('INCREMENT')
 }
 
-// a action with additional arguments
+// an action with additional arguments
 // with ES2015 argument destructuring
 function incrementBy ({ dispatch }, amount) {
   dispatch('INCREMENT', amount)
diff --git a/docs/en/testing.md b/docs/en/testing.md
index 318cbcc55..b4aae115d 100644
--- a/docs/en/testing.md
+++ b/docs/en/testing.md
@@ -164,4 +164,4 @@ mocha test-bundle.js
 
 #### Running in Browser with Karma + karma-webpack
 
-Consult the setup in [vue-loader documentation](http://vuejs.github.io/vue-loader/workflow/testing.html).
+Consult the setup in [vue-loader documentation](http://vue-loader.vuejs.org/en/workflow/testing.html).
diff --git a/docs/en/tutorial.md b/docs/en/tutorial.md
index 1e474a3f5..46c23727d 100644
--- a/docs/en/tutorial.md
+++ b/docs/en/tutorial.md
@@ -250,7 +250,7 @@ You might be wondering - why did we choose to use a getter instead of directly a
 
 1. We may want to define getters with computed values (think totals, averages, etc.).
 2. Many components in a larger app can use the same getter function.
-3. If the value is moved from say `store.count` to `store.counter.value` you'd have to update one getter instead of dozens of components.
+3. If the value is moved from say `store.state.count` to `store.state.counter.value` you'd have to update one getter instead of dozens of components.
 
 These are a few of the benefits of using getters.
 
diff --git a/docs/ja/state.md b/docs/ja/state.md
index 2d3c1edc7..1dd58c789 100644
--- a/docs/ja/state.md
+++ b/docs/ja/state.md
@@ -13,7 +13,7 @@ Vuex は**単一ステートツリー (single state tree)**を使います。つ
 ``` js
 // Vue コンポーネントの定義
 computed: {
-count: function() {
+  count: function() {
     return store.state.count
   }
 }
@@ -67,7 +67,7 @@ count: function() {
 
   特殊な `vuex` オプションブロックについて説明しておきましょう。これは、コンポーネントで利用されるストアの状態が何か記述する場所です。各プロパテイ名は、唯一の引数として、全体のステートツリーを受け取るゲッター関数を指定します。そして、状態の一部を選ぶか、状態から算出される値を返します。返された値は、算出プロパティのように、プロパティ名を使ってコンポーネントにセットされます。
 
-  ほとんどの場合で、"ゲッター( getter )" 関数は、ES2015 のアロー関数を使って、完結に書くことができるでしょう:
+  ほとんどの場合で、"ゲッター( getter )" 関数は、ES2015 のアロー関数を使って、簡潔に書くことができるでしょう:
 
   ``` js
   vuex: {
diff --git a/docs/ja/tutorial.md b/docs/ja/tutorial.md
index 73c70b5c4..58e545d4e 100644
--- a/docs/ja/tutorial.md
+++ b/docs/ja/tutorial.md
@@ -145,7 +145,7 @@ export default {
 
 アクションはコンポーネントから呼び出される関数です。アクション関数は対応するミューテーションをディスパッチすることで、ストアを更新することができます。アクションは更新をディスパッチする前に、その他のデータを読み込むために HTTP バックエンドと通信することも可能です。
 
-`incrementCounter` 関数を持つ、新しいファイル `vuex/action.js` を作成しましょう。
+`incrementCounter` 関数を持つ、新しいファイル `vuex/actions.js` を作成しましょう。
 
 ```js
 // アクションは1番目の引数にストアを受け取ります。
diff --git a/docs/zh-cn/mutations.md b/docs/zh-cn/mutations.md
index d29dbd11d..47df4df01 100644
--- a/docs/zh-cn/mutations.md
+++ b/docs/zh-cn/mutations.md
@@ -99,7 +99,6 @@ import { SOME_MUTATION } from './mutation-types'
 
 const store = new Vuex.Store({
   state: { ... },
-  actions: { ... },
   mutations: {
     // we can use the ES2015 computed property name feature
     // to use a constant as the function name
diff --git a/package.json b/package.json
index 69199db01..594923d6f 100644
--- a/package.json
+++ b/package.json
@@ -20,7 +20,7 @@
     "chat": "cd examples/chat && webpack-dev-server --inline --hot --config ../webpack.shared.config.js",
     "build": "node build/build.js",
     "build-examples": "BABEL_ENV=development webpack --config examples/webpack.build-all.config.js",
-    "unit": "BABEL_ENV=development mocha test/unit/test.js --compilers js:babel-core/register",
+    "unit": "BABEL_ENV=development mocha test/unit/*.js --compilers js:babel-core/register",
     "pree2e": "npm run build-examples",
     "e2e": "casperjs test --concise ./test/e2e",
     "test": "eslint src && npm run unit && npm run e2e",
@@ -47,7 +47,7 @@
     "babel-preset-es2015-rollup": "^1.1.1",
     "babel-preset-stage-2": "^6.1.18",
     "babel-runtime": "^6.0.0",
-    "casperjs": "^1.1.0-beta5",
+    "casperjs": "^1.1.3",
     "chai": "^3.4.1",
     "css-loader": "^0.23.1",
     "eslint": "^2.2.0",
diff --git a/src/index.js b/src/index.js
index 80600b06f..91945b904 100644
--- a/src/index.js
+++ b/src/index.js
@@ -261,11 +261,11 @@ class Store {
   }
 
   /**
-   * Setup mutation check: if the vuex instance's state is mutated
+   * Setup mutation check: if the Vuex instance's state is mutated
    * outside of a mutation handler, we throw en error. This effectively
-   * enforces all mutations to the state to be trackable and hot-reloadble.
+   * enforces all mutations to the state to be trackable and hot-reloadable.
    * However, this comes at a run time cost since we are doing a deep
-   * watch on the entire state tree, so it is only enalbed with the
+   * watch on the entire state tree, so it is only enabled if the
    * strict option is set to true.
    */
 
diff --git a/src/plugins/logger.js b/src/plugins/logger.js
index 583620837..1bef55cc7 100644
--- a/src/plugins/logger.js
+++ b/src/plugins/logger.js
@@ -1,18 +1,20 @@
 // Credits: borrowed code from fcomb/redux-logger
 
+import { deepCopy } from '../util'
+
 export default function createLogger ({
   collapsed = true,
   transformer = state => state,
   mutationTransformer = mut => mut
 } = {}) {
   return store => {
-    let prevState = JSON.parse(JSON.stringify(store.state))
+    let prevState = deepCopy(store.state)
 
     store.subscribe((mutation, state) => {
       if (typeof console === 'undefined') {
         return
       }
-      const nextState = JSON.parse(JSON.stringify(state))
+      const nextState = deepCopy(state)
       const time = new Date()
       const formattedTime = ` @ ${pad(time.getHours(), 2)}:${pad(time.getMinutes(), 2)}:${pad(time.getSeconds(), 2)}.${pad(time.getMilliseconds(), 3)}`
       const formattedMutation = mutationTransformer(mutation)
@@ -28,9 +30,9 @@ export default function createLogger ({
         console.log(message)
       }
 
-      console.log('%c prev state', 'color: #9E9E9E; font-weight: bold', prevState)
+      console.log('%c prev state', 'color: #9E9E9E; font-weight: bold', transformer(prevState))
       console.log('%c mutation', 'color: #03A9F4; font-weight: bold', formattedMutation)
-      console.log('%c next state', 'color: #4CAF50; font-weight: bold', nextState)
+      console.log('%c next state', 'color: #4CAF50; font-weight: bold', transformer(nextState))
 
       try {
         console.groupEnd()
diff --git a/src/util.js b/src/util.js
index fea7d5e46..c8729791a 100644
--- a/src/util.js
+++ b/src/util.js
@@ -25,6 +25,54 @@ export function mergeObjects (arr) {
   }, {})
 }
 
+/**
+ * Get the first item that pass the test
+ * by second argument function
+ *
+ * @param {Array} list
+ * @param {Function} f
+ * @return {*}
+ */
+function find (list, f) {
+  return list.filter(f)[0]
+}
+
+/**
+ * Deep copy the given object considering circular structure.
+ * This function caches all nested objects and its copies.
+ * If it detects circular structure, use cached copy to avoid infinite loop.
+ *
+ * @param {*} obj
+ * @param {Array<Object>} cache
+ * @return {*}
+ */
+export function deepCopy (obj, cache = []) {
+  // just return if obj is immutable value
+  if (obj === null || typeof obj !== 'object') {
+    return obj
+  }
+
+  // if obj is hit, it is in circular structure
+  const hit = find(cache, c => c.original === obj)
+  if (hit) {
+    return hit.copy
+  }
+
+  const copy = Array.isArray(obj) ? [] : {}
+  // put the copy into cache at first
+  // because we want to refer it in recursive deepCopy
+  cache.push({
+    original: obj,
+    copy
+  })
+
+  Object.keys(obj).forEach(key => {
+    copy[key] = deepCopy(obj[key], cache)
+  })
+
+  return copy
+}
+
 /**
  * Check whether the given value is Object or not
  *
diff --git a/test/e2e/todomvc.js b/test/e2e/todomvc.js
index c7085174c..811905d67 100644
--- a/test/e2e/todomvc.js
+++ b/test/e2e/todomvc.js
@@ -2,6 +2,7 @@ casper.test.begin('todomvc', 57, function (test) {
   casper
   .start('examples/todomvc/index.html')
   .then(function () {
+    this.viewport(1000, 1000) // for appearing destroy button by mouse hover
     test.assertNotVisible('.main', '.main should be hidden')
     test.assertNotVisible('.footer', '.footer should be hidden')
     test.assertElementCount('.filters .selected', 1, 'should have one filter selected')
@@ -29,7 +30,7 @@ casper.test.begin('todomvc', 57, function (test) {
     test.assertVisible('.main', '.main should now be visible')
     test.assertVisible('.footer', '.footer should now be visible')
     test.assertNotVisible('.clear-completed', '.clear-completed should be hidden')
-    test.assertField({type: 'css', path: '.new-todo'}, '', 'new todo input should be reset')
+    test.assertField({ type: 'css', path: '.new-todo' }, '', 'new todo input should be reset')
   })
 
   // add another item ---------------------------------------------------
@@ -88,6 +89,9 @@ casper.test.begin('todomvc', 57, function (test) {
 
   // remove a completed item --------------------------------------------
 
+  .then(function () {
+    this.mouse.move('.todo:nth-child(1)')
+  })
   .thenClick('.todo:nth-child(1) .destroy', function () {
     test.assertElementCount('.todo', 4, 'should have 4 items now')
     test.assertElementCount('.todo.completed', 2, 'should have 2 item completed')
@@ -96,6 +100,9 @@ casper.test.begin('todomvc', 57, function (test) {
 
   // remove a incompleted item ------------------------------------------
 
+  .then(function () {
+    this.mouse.move('.todo:nth-child(2)')
+  })
   .thenClick('.todo:nth-child(2) .destroy', function () {
     test.assertElementCount('.todo', 3, 'should have 3 items now')
     test.assertElementCount('.todo.completed', 2, 'should have 2 item completed')
diff --git a/test/unit/util.js b/test/unit/util.js
new file mode 100644
index 000000000..1ce62fea3
--- /dev/null
+++ b/test/unit/util.js
@@ -0,0 +1,42 @@
+import { expect } from 'chai'
+import { deepCopy } from '../../src/util'
+
+describe('util', () => {
+  it('deepCopy: nornal structure', () => {
+    const original = {
+      a: 1,
+      b: 'string',
+      c: true,
+      d: null,
+      e: undefined
+    }
+    const copy = deepCopy(original)
+
+    expect(copy).to.deep.equal(original)
+  })
+
+  it('deepCopy: nested structure', () => {
+    const original = {
+      a: {
+        b: 1,
+        c: [2, 3, {
+          d: 4
+        }]
+      }
+    }
+    const copy = deepCopy(original)
+
+    expect(copy).to.deep.equal(original)
+  })
+
+  it('deepCopy: circular structure', () => {
+    const original = {
+      a: 1
+    }
+    original.circular = original
+
+    const copy = deepCopy(original)
+
+    expect(copy).to.deep.equal(original)
+  })
+})