Vue.js/dist/vue.js

/*!
 * Vue.js v2.0.0-beta.1
 * (c) 2014-2016 Evan You
 * Released under the MIT License.
 */
(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global.Vue = factory());
}(this, function () { 'use strict';

  /**
   * Convert a value to a string that is actually rendered.
   */
  function _toString(val) {
    return val == null ? '' : typeof val === 'object' ? JSON.stringify(val, null, 2) : String(val);
  }

  /**
   * Convert a input value to a number for persistence.
   * If the conversion fails, return original string.
   */
  function toNumber(val) {
    var n = parseFloat(val, 10);
    return n || n === 0 ? n : val;
  }

  /**
   * Make a map and return a function for checking if a key
   * is in that map.
   */
  function makeMap(str, expectsLowerCase) {
    var map = Object.create(null);
    var list = str.split(',');
    for (var i = 0; i < list.length; i++) {
      map[list[i]] = true;
    }
    return expectsLowerCase ? function (val) {
      return map[val.toLowerCase()];
    } : function (val) {
      return map[val];
    };
  }

  /**
   * Check if a tag is a built-in tag.
   */
  var isBuiltInTag = makeMap('slot,component,render,transition', true);

  /**
   * Remove an item from an array
   */
  function remove(arr, item) {
    if (arr.length) {
      var index = arr.indexOf(item);
      if (index > -1) {
        return arr.splice(index, 1);
      }
    }
  }

  /**
   * Check whether the object has the property.
   */
  var hasOwnProperty = Object.prototype.hasOwnProperty;
  function hasOwn(obj, key) {
    return hasOwnProperty.call(obj, key);
  }

  /**
   * Check if value is primitive
   */
  function isPrimitive(value) {
    return typeof value === 'string' || typeof value === 'number';
  }

  /**
   * Create a cached version of a pure function.
   */
  function cached(fn) {
    var cache = Object.create(null);
    return function cachedFn(str) {
      var hit = cache[str];
      return hit || (cache[str] = fn(str));
    };
  }

  /**
   * Camelize a hyphen-delmited string.
   */
  var camelizeRE = /-(\w)/g;
  var camelize = cached(function (str) {
    return str.replace(camelizeRE, function (_, c) {
      return c ? c.toUpperCase() : '';
    });
  });

  /**
   * Capitalize a string.
   */
  var capitalize = cached(function (str) {
    return str.charAt(0).toUpperCase() + str.slice(1);
  });

  /**
   * Hyphenate a camelCase string.
   */
  var hyphenateRE = /([^-])([A-Z])/g;
  var hyphenate = cached(function (str) {
    return str.replace(hyphenateRE, '$1-$2').replace(hyphenateRE, '$1-$2').toLowerCase();
  });

  /**
   * Simple bind, faster than native
   */
  function bind(fn, ctx) {
    return function (a) {
      var l = arguments.length;
      return l ? l > 1 ? fn.apply(ctx, arguments) : fn.call(ctx, a) : fn.call(ctx);
    };
  }

  /**
   * Convert an Array-like object to a real Array.
   */
  function toArray(list, start) {
    start = start || 0;
    var i = list.length - start;
    var ret = new Array(i);
    while (i--) {
      ret[i] = list[i + start];
    }
    return ret;
  }

  /**
   * Mix properties into target object.
   */
  function extend(to, _from) {
    for (var _key in _from) {
      to[_key] = _from[_key];
    }
    return to;
  }

  /**
   * Quick object check - this is primarily used to tell
   * Objects from primitive values when we know the value
   * is a JSON-compliant type.
   */
  function isObject(obj) {
    return obj !== null && typeof obj === 'object';
  }

  /**
   * Strict object type check. Only returns true
   * for plain JavaScript objects.
   */
  var toString = Object.prototype.toString;
  var OBJECT_STRING = '[object Object]';
  function isPlainObject(obj) {
    return toString.call(obj) === OBJECT_STRING;
  }

  /**
   * Merge an Array of Objects into a single Object.
   */
  function toObject(arr) {
    var res = arr[0] || {};
    for (var i = 1; i < arr.length; i++) {
      if (arr[i]) {
        extend(res, arr[i]);
      }
    }
    return res;
  }

  /**
   * Perform no operation.
   */
  function noop() {}

  /**
   * Always return false.
   */
  var no = function no() {
    return false;
  };

  /**
   * Generate a static keys string from compiler modules.
   */
  function genStaticKeys(modules) {
    return modules.reduce(function (keys, m) {
      return keys.concat(m.staticKeys || []);
    }, []).join(',');
  }

  var config = {
    /**
     * Option merge strategies (used in core/util/options)
     */
    optionMergeStrategies: Object.create(null),

    /**
     * Whether to suppress warnings.
     */
    silent: false,

    /**
     * Whether to enable devtools
     */
    devtools: "development" !== 'production',

    /**
     * Error handler for watcher errors
     */
    errorHandler: null,

    /**
     * Ignore certain custom elements
     */
    ignoredElements: null,

    /**
     * Custom user key aliases for v-on
     */
    keyCodes: Object.create(null),

    /**
     * Check if a tag is reserved so that it cannot be registered as a
     * component. This is platform-dependent and may be overwritten.
     */
    isReservedTag: no,

    /**
     * Check if a tag is an unknown element.
     * Platform-dependent.
     */
    isUnknownElement: no,

    /**
     * Get the namespace of an element
     */
    getTagNamespace: noop,

    /**
     * Check if an attribute must be bound using property, e.g. value
     * Platform-dependent.
     */
    mustUseProp: no,

    /**
     * List of asset types that a component can own.
     */
    _assetTypes: ['component', 'directive', 'transition', 'filter'],

    /**
     * List of lifecycle hooks.
     */
    _lifecycleHooks: ['beforeCreate', 'created', 'beforeMount', 'mounted', 'beforeUpdate', 'updated', 'beforeDestroy', 'destroyed', 'activated', 'deactivated'],

    /**
     * Max circular updates allowed in a scheduler flush cycle.
     */
    _maxUpdateCount: 100,

    /**
     * Server rendering?
     */
    _isServer: "client" === 'server'
  };

  /**
   * Check if a string starts with $ or _
   */
  function isReserved(str) {
    var c = (str + '').charCodeAt(0);
    return c === 0x24 || c === 0x5F;
  }

  /**
   * Define a property.
   */
  function def(obj, key, val, enumerable) {
    Object.defineProperty(obj, key, {
      value: val,
      enumerable: !!enumerable,
      writable: true,
      configurable: true
    });
  }

  /**
   * Parse simple path.
   */
  var bailRE = /[^\w\.\$]/;
  function parsePath(path) {
    if (bailRE.test(path)) {
      return;
    } else {
      var _ret = function () {
        var segments = path.split('.');
        return {
          v: function v(obj) {
            for (var i = 0; i < segments.length; i++) {
              if (!obj) return;
              obj = obj[segments[i]];
            }
            return obj;
          }
        };
      }();

      if (typeof _ret === "object") return _ret.v;
    }
  }

  /* global MutationObserver */
  // can we use __proto__?
  var hasProto = '__proto__' in {};

  // Browser environment sniffing
  var inBrowser = typeof window !== 'undefined' && Object.prototype.toString.call(window) !== '[object Object]';

  // detect devtools
  var devtools = inBrowser && window.__VUE_DEVTOOLS_GLOBAL_HOOK__;

  // UA sniffing for working around browser-specific quirks
  var UA = inBrowser && window.navigator.userAgent.toLowerCase();
  var isIos = UA && /(iphone|ipad|ipod|ios)/i.test(UA);
  var iosVersionMatch = UA && isIos && UA.match(/os ([\d_]+)/);
  var iosVersion = iosVersionMatch && iosVersionMatch[1].split('_');

  // MutationObserver is unreliable in iOS 9.3 UIWebView
  // detecting it by checking presence of IndexedDB
  // ref #3027
  var hasMutationObserverBug = iosVersion && Number(iosVersion[0]) >= 9 && Number(iosVersion[1]) >= 3 && !window.indexedDB;

  /**
   * Defer a task to execute it asynchronously. Ideally this
   * should be executed as a microtask, so we leverage
   * MutationObserver if it's available, and fallback to
   * setTimeout(0).
   *
   * @param {Function} cb
   * @param {Object} ctx
   */
  var nextTick = function () {
    var callbacks = [];
    var pending = false;
    var timerFunc = void 0;
    function nextTickHandler() {
      pending = false;
      var copies = callbacks.slice(0);
      callbacks = [];
      for (var i = 0; i < copies.length; i++) {
        copies[i]();
      }
    }

    /* istanbul ignore else */
    if (typeof MutationObserver !== 'undefined' && !hasMutationObserverBug) {
      (function () {
        var counter = 1;
        var observer = new MutationObserver(nextTickHandler);
        var textNode = document.createTextNode(String(counter));
        observer.observe(textNode, {
          characterData: true
        });
        timerFunc = function timerFunc() {
          counter = (counter + 1) % 2;
          textNode.data = String(counter);
        };
      })();
    } else {
      // webpack attempts to inject a shim for setImmediate
      // if it is used as a global, so we have to work around that to
      // avoid bundling unnecessary code.
      var context = inBrowser ? window : typeof global !== 'undefined' ? global : {};
      timerFunc = context.setImmediate || setTimeout;
    }
    return function (cb, ctx) {
      var func = ctx ? function () {
        cb.call(ctx);
      } : cb;
      callbacks.push(func);
      if (pending) return;
      pending = true;
      timerFunc(nextTickHandler, 0);
    };
  }();

  var _Set = void 0;
  /* istanbul ignore if */
  if (typeof Set !== 'undefined' && /native code/.test(Set.toString())) {
    // use native Set when available.
    _Set = Set;
  } else {
    // a non-standard Set polyfill that only works with primitive keys.
    _Set = function () {
      function Set() {
        this.set = Object.create(null);
      }

      Set.prototype.has = function has(key) {
        return this.set[key] !== undefined;
      };

      Set.prototype.add = function add(key) {
        this.set[key] = 1;
      };

      Set.prototype.clear = function clear() {
        this.set = Object.create(null);
      };

      return Set;
    }();
  }

  var hasProxy = void 0;
  var proxyHandlers = void 0;
  var initProxy = void 0;
  if ("development" !== 'production') {
    (function () {
      var allowedGlobals = makeMap('Infinity,undefined,NaN,isFinite,isNaN,' + 'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' + 'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' + 'require,__webpack_require__' // for Webpack/Browserify
      );

      hasProxy = typeof Proxy !== 'undefined' && Proxy.toString().match(/native code/);

      proxyHandlers = {
        has: function has(target, key) {
          var has = key in target;
          var isAllowedGlobal = allowedGlobals(key);
          if (!has && !isAllowedGlobal) {
            warn('Trying to access non-existent property "' + key + '" while rendering. ' + 'Make sure to declare reactive data properties in the data option.', target);
          }
          return !isAllowedGlobal;
        }
      };

      initProxy = function initProxy(vm) {
        if (hasProxy) {
          vm._renderProxy = new Proxy(vm, proxyHandlers);
        } else {
          vm._renderProxy = vm;
        }
      };
    })();
  }

  var uid$2 = 0;

  /**
   * A dep is an observable that can have multiple
   * directives subscribing to it.
   */

  var Dep = function () {
    function Dep() {
      this.id = uid$2++;
      this.subs = [];
    }

    Dep.prototype.addSub = function addSub(sub) {
      this.subs.push(sub);
    };

    Dep.prototype.removeSub = function removeSub(sub) {
      remove(this.subs, sub);
    };

    Dep.prototype.depend = function depend() {
      if (Dep.target) {
        Dep.target.addDep(this);
      }
    };

    Dep.prototype.notify = function notify() {
      // stablize the subscriber list first
      var subs = this.subs.slice();
      for (var i = 0, l = subs.length; i < l; i++) {
        subs[i].update();
      }
    };

    return Dep;
  }();

  Dep.target = null;
  var targetStack = [];

  function pushTarget(_target) {
    if (Dep.target) targetStack.push(Dep.target);
    Dep.target = _target;
  }

  function popTarget() {
    Dep.target = targetStack.pop();
  }

  // We have two separate queues: one for internal component re-render updates
  // and one for user watcher registered via $watch(). We want to guarantee
  // re-render updates to be called before user watchers so that when user
  // watchers are triggered, the DOM would already be in updated state.

  var queue = [];
  var userQueue = [];
  var has = {};
  var circular = {};
  var waiting = false;

  /**
   * Reset the scheduler's state.
   */
  function resetSchedulerState() {
    queue.length = 0;
    userQueue.length = 0;
    has = {};
    if ("development" !== 'production') {
      circular = {};
    }
    waiting = false;
  }

  /**
   * Flush both queues and run the watchers.
   */
  function flushSchedulerQueue() {
    runSchedulerQueue(queue.sort(queueSorter));
    runSchedulerQueue(userQueue);
    // user watchers triggered more watchers,
    // keep flushing until it depletes
    if (queue.length) {
      return flushSchedulerQueue();
    }
    // devtool hook
    /* istanbul ignore if */
    if (devtools && config.devtools) {
      devtools.emit('flush');
    }
    resetSchedulerState();
  }

  /**
   * Sort queue before flush.
   * This ensures components are updated from parent to child
   * so there will be no duplicate updates, e.g. a child was
   * pushed into the queue first and then its parent's props
   * changed.
   */
  function queueSorter(a, b) {
    return a.id - b.id;
  }

  /**
   * Run the watchers in a single queue.
   */
  function runSchedulerQueue(queue) {
    // do not cache length because more watchers might be pushed
    // as we run existing watchers
    for (var i = 0; i < queue.length; i++) {
      var watcher = queue[i];
      var id = watcher.id;
      has[id] = null;
      watcher.run();
      // in dev build, check and stop circular updates.
      if ("development" !== 'production' && has[id] != null) {
        circular[id] = (circular[id] || 0) + 1;
        if (circular[id] > config._maxUpdateCount) {
          warn('You may have an infinite update loop for watcher ' + 'with expression "' + watcher.expression + '"', watcher.vm);
          break;
        }
      }
    }
    queue.length = 0;
  }

  /**
   * Push a watcher into the watcher queue.
   * Jobs with duplicate IDs will be skipped unless it's
   * pushed when the queue is being flushed.
   */
  function queueWatcher(watcher) {
    var id = watcher.id;
    if (has[id] == null) {
      // push watcher into appropriate queue
      var q = watcher.user ? userQueue : queue;
      has[id] = true;
      q.push(watcher);
      // queue the flush
      if (!waiting) {
        waiting = true;
        nextTick(flushSchedulerQueue);
      }
    }
  }

  var uid$1 = 0;

  /**
   * A watcher parses an expression, collects dependencies,
   * and fires callback when the expression value changes.
   * This is used for both the $watch() api and directives.
   */

  var Watcher = function () {
    function Watcher(vm, expOrFn, cb) {
      var options = arguments.length <= 3 || arguments[3] === undefined ? {} : arguments[3];

      this.vm = vm;
      vm._watchers.push(this);
      // options
      this.deep = !!options.deep;
      this.user = !!options.user;
      this.lazy = !!options.lazy;
      this.sync = !!options.sync;
      this.expression = expOrFn.toString();
      this.cb = cb;
      this.id = ++uid$1; // uid for batching
      this.active = true;
      this.dirty = this.lazy; // for lazy watchers
      this.deps = [];
      this.newDeps = [];
      this.depIds = new _Set();
      this.newDepIds = new _Set();
      // parse expression for getter
      if (typeof expOrFn === 'function') {
        this.getter = expOrFn;
      } else {
        this.getter = parsePath(expOrFn);
        if (!this.getter) {
          this.getter = function () {};
          "development" !== 'production' && warn('Failed watching path: "' + expOrFn + '" ' + 'Watcher only accepts simple dot-delimited paths. ' + 'For full control, use a function instead.', vm);
        }
      }
      this.value = this.lazy ? undefined : this.get();
    }

    /**
     * Evaluate the getter, and re-collect dependencies.
     */


    Watcher.prototype.get = function get() {
      pushTarget(this);
      var value = void 0;
      try {
        value = this.getter.call(this.vm, this.vm);
      } catch (e) {
        if ("development" !== 'production') {
          if (this.user) {
            warn('Error when evaluating watcher with getter: ' + this.expression, this.vm);
          } else {
            warn('Error during component render', this.vm);
          }
        }
        /* istanbul ignore else */
        if (config.errorHandler) {
          config.errorHandler.call(null, e, this.vm);
        } else {
          throw e;
        }
        // return old value when evaluation fails so the current UI is preserved
        // if the error was somehow handled by user
        value = this.value;
      }
      // "touch" every property so they are all tracked as
      // dependencies for deep watching
      if (this.deep) {
        traverse(value);
      }
      popTarget();
      this.cleanupDeps();
      return value;
    };

    /**
     * Add a dependency to this directive.
     */


    Watcher.prototype.addDep = function addDep(dep) {
      var id = dep.id;
      if (!this.newDepIds.has(id)) {
        this.newDepIds.add(id);
        this.newDeps.push(dep);
        if (!this.depIds.has(id)) {
          dep.addSub(this);
        }
      }
    };

    /**
     * Clean up for dependency collection.
     */


    Watcher.prototype.cleanupDeps = function cleanupDeps() {
      var i = this.deps.length;
      while (i--) {
        var dep = this.deps[i];
        if (!this.newDepIds.has(dep.id)) {
          dep.removeSub(this);
        }
      }
      var tmp = this.depIds;
      this.depIds = this.newDepIds;
      this.newDepIds = tmp;
      this.newDepIds.clear();
      tmp = this.deps;
      this.deps = this.newDeps;
      this.newDeps = tmp;
      this.newDeps.length = 0;
    };

    /**
     * Subscriber interface.
     * Will be called when a dependency changes.
     */


    Watcher.prototype.update = function update() {
      /* istanbul ignore else */
      if (this.lazy) {
        this.dirty = true;
      } else if (this.sync) {
        this.run();
      } else {
        queueWatcher(this);
      }
    };

    /**
     * Scheduler job interface.
     * Will be called by the scheduler.
     */


    Watcher.prototype.run = function run() {
      if (this.active) {
        var value = this.get();
        if (value !== this.value ||
        // Deep watchers and watchers on Object/Arrays should fire even
        // when the value is the same, because the value may
        // have mutated.
        isObject(value) || this.deep) {
          // set new value
          var oldValue = this.value;
          this.value = value;
          if (this.user) {
            try {
              this.cb.call(this.vm, value, oldValue);
            } catch (e) {
              "development" !== 'production' && warn('Error in watcher "' + this.expression + '"', this.vm);
              /* istanbul ignore else */
              if (config.errorHandler) {
                config.errorHandler.call(null, e, this.vm);
              } else {
                throw e;
              }
            }
          } else {
            this.cb.call(this.vm, value, oldValue);
          }
        }
      }
    };

    /**
     * Evaluate the value of the watcher.
     * This only gets called for lazy watchers.
     */


    Watcher.prototype.evaluate = function evaluate() {
      this.value = this.get();
      this.dirty = false;
    };

    /**
     * Depend on all deps collected by this watcher.
     */


    Watcher.prototype.depend = function depend() {
      var i = this.deps.length;
      while (i--) {
        this.deps[i].depend();
      }
    };

    /**
     * Remove self from all dependencies' subcriber list.
     */


    Watcher.prototype.teardown = function teardown() {
      if (this.active) {
        // remove self from vm's watcher list
        // this is a somewhat expensive operation so we skip it
        // if the vm is being destroyed or is performing a v-for
        // re-render (the watcher list is then filtered by v-for).
        if (!this.vm._isBeingDestroyed && !this.vm._vForRemoving) {
          remove(this.vm._watchers, this);
        }
        var i = this.deps.length;
        while (i--) {
          this.deps[i].removeSub(this);
        }
        this.active = false;
      }
    };

    return Watcher;
  }();

  var seenObjects = new _Set();
  function traverse(val, seen) {
    var i = void 0,
        keys = void 0;
    if (!seen) {
      seen = seenObjects;
      seen.clear();
    }
    var isA = Array.isArray(val);
    var isO = isObject(val);
    if ((isA || isO) && Object.isExtensible(val)) {
      if (val.__ob__) {
        var depId = val.__ob__.dep.id;
        if (seen.has(depId)) {
          return;
        } else {
          seen.add(depId);
        }
      }
      if (isA) {
        i = val.length;
        while (i--) {
          traverse(val[i], seen);
        }
      } else if (isO) {
        keys = Object.keys(val);
        i = keys.length;
        while (i--) {
          traverse(val[keys[i]], seen);
        }
      }
    }
  }

  var arrayProto = Array.prototype;
  var arrayMethods = Object.create(arrayProto)

  /**
   * Intercept mutating methods and emit events
   */
  ;['push', 'pop', 'shift', 'unshift', 'splice', 'sort', 'reverse'].forEach(function (method) {
    // cache original method
    var original = arrayProto[method];
    def(arrayMethods, method, function mutator() {
      // avoid leaking arguments:
      // http://jsperf.com/closure-with-arguments
      var i = arguments.length;
      var args = new Array(i);
      while (i--) {
        args[i] = arguments[i];
      }
      var result = original.apply(this, args);
      var ob = this.__ob__;
      var inserted = void 0;
      switch (method) {
        case 'push':
          inserted = args;
          break;
        case 'unshift':
          inserted = args;
          break;
        case 'splice':
          inserted = args.slice(2);
          break;
      }
      if (inserted) ob.observeArray(inserted);
      // notify change
      ob.dep.notify();
      return result;
    });
  });

  var arrayKeys = Object.getOwnPropertyNames(arrayMethods);

  /**
   * By default, when a reactive property is set, the new value is
   * also converted to become reactive. However when passing down props,
   * we don't want to force conversion because the value may be a nested value
   * under a frozen data structure. Converting it would defeat the optimization.
   */
  var observerState = {
    shouldConvert: true,
    isSettingProps: false
  };

  /**
   * Observer class that are attached to each observed
   * object. Once attached, the observer converts target
   * object's property keys into getter/setters that
   * collect dependencies and dispatches updates.
   */
  var Observer = function () {
    // number of vms that has this object as root $data

    function Observer(value) {
      this.value = value;
      this.dep = new Dep();
      this.vmCount = 0;
      def(value, '__ob__', this);
      if (Array.isArray(value)) {
        var augment = hasProto ? protoAugment : copyAugment;
        augment(value, arrayMethods, arrayKeys);
        this.observeArray(value);
      } else {
        this.walk(value);
      }
    }

    /**
     * Walk through each property and convert them into
     * getter/setters. This method should only be called when
     * value type is Object.
     */


    Observer.prototype.walk = function walk(obj) {
      var val = this.value;
      for (var key in obj) {
        defineReactive(val, key, obj[key]);
      }
    };

    /**
     * Observe a list of Array items.
     */


    Observer.prototype.observeArray = function observeArray(items) {
      for (var i = 0, l = items.length; i < l; i++) {
        observe(items[i]);
      }
    };

    return Observer;
  }();

  // helpers

  /**
   * Augment an target Object or Array by intercepting
   * the prototype chain using __proto__
   */
  function protoAugment(target, src) {
    /* eslint-disable no-proto */
    target.__proto__ = src;
    /* eslint-enable no-proto */
  }

  /**
   * Augment an target Object or Array by defining
   * hidden properties.
   *
   * istanbul ignore next
   */
  function copyAugment(target, src, keys) {
    for (var i = 0, l = keys.length; i < l; i++) {
      var key = keys[i];
      def(target, key, src[key]);
    }
  }

  /**
   * Attempt to create an observer instance for a value,
   * returns the new observer if successfully observed,
   * or the existing observer if the value already has one.
   */
  function observe(value) {
    if (!isObject(value)) {
      return;
    }
    var ob = void 0;
    if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
      ob = value.__ob__;
    } else if (observerState.shouldConvert && !config._isServer && (Array.isArray(value) || isPlainObject(value)) && Object.isExtensible(value) && !value._isVue) {
      ob = new Observer(value);
    }
    return ob;
  }

  /**
   * Define a reactive property on an Object.
   */
  function defineReactive(obj, key, val, customSetter) {
    var dep = new Dep();

    var property = Object.getOwnPropertyDescriptor(obj, key);
    if (property && property.configurable === false) {
      return;
    }

    // cater for pre-defined getter/setters
    var getter = property && property.get;
    var setter = property && property.set;

    var childOb = observe(val);
    Object.defineProperty(obj, key, {
      enumerable: true,
      configurable: true,
      get: function reactiveGetter() {
        var value = getter ? getter.call(obj) : val;
        if (Dep.target) {
          dep.depend();
          if (childOb) {
            childOb.dep.depend();
          }
          if (Array.isArray(value)) {
            for (var e, i = 0, l = value.length; i < l; i++) {
              e = value[i];
              e && e.__ob__ && e.__ob__.dep.depend();
            }
          }
        }
        return value;
      },
      set: function reactiveSetter(newVal) {
        var value = getter ? getter.call(obj) : val;
        if (newVal === value) {
          return;
        }
        if ("development" !== 'production' && customSetter) {
          customSetter();
        }
        if (setter) {
          setter.call(obj, newVal);
        } else {
          val = newVal;
        }
        childOb = observe(newVal);
        dep.notify();
      }
    });
  }

  /**
   * Set a property on an object. Adds the new property and
   * triggers change notification if the property doesn't
   * already exist.
   */
  function set(obj, key, val) {
    if (Array.isArray(obj)) {
      obj.splice(key, 1, val);
      return val;
    }
    if (hasOwn(obj, key)) {
      obj[key] = val;
      return;
    }
    var ob = obj.__ob__;
    if (obj._isVue || ob && ob.vmCount) {
      "development" !== 'production' && warn('Avoid adding reactive properties to a Vue instance or its root $data ' + 'at runtime - delcare it upfront in the data option.');
      return;
    }
    if (!ob) {
      obj[key] = val;
      return;
    }
    defineReactive(ob.value, key, val);
    ob.dep.notify();
    return val;
  }

  /**
   * Delete a property and trigger change if necessary.
   */
  function del(obj, key) {
    var ob = obj.__ob__;
    if (obj._isVue || ob && ob.vmCount) {
      "development" !== 'production' && warn('Avoid deleting properties on a Vue instance or its root $data ' + '- just set it to null.');
      return;
    }
    if (!hasOwn(obj, key)) {
      return;
    }
    delete obj[key];
    if (!ob) {
      return;
    }
    ob.dep.notify();
  }

  function initState(vm) {
    vm._watchers = [];
    initProps(vm);
    initData(vm);
    initComputed(vm);
    initMethods(vm);
    initWatch(vm);
  }

  function initProps(vm) {
    var props = vm.$options.props;
    var propsData = vm.$options.propsData;
    if (props) {
      var keys = vm.$options._propKeys = Object.keys(props);
      var isRoot = !vm.$parent;
      // root instance props should be converted
      observerState.shouldConvert = isRoot;

      var _loop = function _loop(i) {
        var key = keys[i];
        /* istanbul ignore else */
        if ("development" !== 'production') {
          defineReactive(vm, key, validateProp(key, props, propsData, vm), function () {
            if (vm.$parent && !observerState.isSettingProps) {
              warn('Avoid mutating a prop directly since the value will be ' + 'overwritten whenever the parent component re-renders. ' + 'Instead, use a data or computed property based on the prop\'s ' + ('value. Prop being mutated: "' + key + '"'), vm);
            }
          });
        } else {}
      };

      for (var i = 0; i < keys.length; i++) {
        _loop(i);
      }
      observerState.shouldConvert = true;
    }
  }

  function initData(vm) {
    var data = vm.$options.data;
    data = vm._data = typeof data === 'function' ? data.call(vm) : data || {};
    if (!isPlainObject(data)) {
      data = {};
      "development" !== 'production' && warn('data functions should return an object.', vm);
    }
    // proxy data on instance
    var keys = Object.keys(data);
    var props = vm.$options.props;
    var i = keys.length;
    while (i--) {
      if (props && hasOwn(props, keys[i])) {
        "development" !== 'production' && warn('The data property "' + keys[i] + '" is already declared as a prop. ' + 'Use prop default value instead.', vm);
      } else {
        proxy(vm, keys[i]);
      }
    }
    // observe data
    observe(data);
    data.__ob__ && data.__ob__.vmCount++;
  }

  var computedSharedDefinition = {
    enumerable: true,
    configurable: true,
    get: noop,
    set: noop
  };

  function initComputed(vm) {
    var computed = vm.$options.computed;
    if (computed) {
      for (var _key in computed) {
        var userDef = computed[_key];
        if (typeof userDef === 'function') {
          computedSharedDefinition.get = makeComputedGetter(userDef, vm);
          computedSharedDefinition.set = noop;
        } else {
          computedSharedDefinition.get = userDef.get ? userDef.cache !== false ? makeComputedGetter(userDef.get, vm) : bind(userDef.get, vm) : noop;
          computedSharedDefinition.set = userDef.set ? bind(userDef.set, vm) : noop;
        }
        Object.defineProperty(vm, _key, computedSharedDefinition);
      }
    }
  }

  function makeComputedGetter(getter, owner) {
    var watcher = new Watcher(owner, getter, noop, {
      lazy: true
    });
    return function computedGetter() {
      if (watcher.dirty) {
        watcher.evaluate();
      }
      if (Dep.target) {
        watcher.depend();
      }
      return watcher.value;
    };
  }

  function initMethods(vm) {
    var methods = vm.$options.methods;
    if (methods) {
      for (var _key2 in methods) {
        vm[_key2] = bind(methods[_key2], vm);
      }
    }
  }

  function initWatch(vm) {
    var watch = vm.$options.watch;
    if (watch) {
      for (var _key3 in watch) {
        var handler = watch[_key3];
        if (Array.isArray(handler)) {
          for (var i = 0; i < handler.length; i++) {
            createWatcher(vm, _key3, handler[i]);
          }
        } else {
          createWatcher(vm, _key3, handler);
        }
      }
    }
  }

  function createWatcher(vm, key, handler) {
    var options = void 0;
    if (isPlainObject(handler)) {
      options = handler;
      handler = handler.handler;
    }
    if (typeof handler === 'string') {
      handler = vm[handler];
    }
    vm.$watch(key, handler, options);
  }

  function stateMixin(Vue) {
    // flow somehow has problems with directly declared definition object
    // when using Object.defineProperty, so we have to procedurally build up
    // the object here.
    var dataDef = {};
    dataDef.get = function () {
      return this._data;
    };
    if ("development" !== 'production') {
      dataDef.set = function (newData) {
        warn('Avoid replacing instance root $data. ' + 'Use nested data properties instead.', this);
      };
    }
    Object.defineProperty(Vue.prototype