/files/vue/1.0.18/vue.common.js

/*!
 * Vue.js v1.0.18
 * (c) 2016 Evan You
 * Released under the MIT License.
 */
'use strict';

function set(obj, key, val) {
  if (hasOwn(obj, key)) {
    obj[key] = val;
    return;
  }
  if (obj._isVue) {
    set(obj._data, key, val);
    return;
  }
  var ob = obj.__ob__;
  if (!ob) {
    obj[key] = val;
    return;
  }
  ob.convert(key, val);
  ob.dep.notify();
  if (ob.vms) {
    var i = ob.vms.length;
    while (i--) {
      var vm = ob.vms[i];
      vm._proxy(key);
      vm._digest();
    }
  }
  return val;
}

/**
 * Delete a property and trigger change if necessary.
 *
 * @param {Object} obj
 * @param {String} key
 */

function del(obj, key) {
  if (!hasOwn(obj, key)) {
    return;
  }
  delete obj[key];
  var ob = obj.__ob__;
  if (!ob) {
    return;
  }
  ob.dep.notify();
  if (ob.vms) {
    var i = ob.vms.length;
    while (i--) {
      var vm = ob.vms[i];
      vm._unproxy(key);
      vm._digest();
    }
  }
}

var hasOwnProperty = Object.prototype.hasOwnProperty;
/**
 * Check whether the object has the property.
 *
 * @param {Object} obj
 * @param {String} key
 * @return {Boolean}
 */

function hasOwn(obj, key) {
  return hasOwnProperty.call(obj, key);
}

/**
 * Check if an expression is a literal value.
 *
 * @param {String} exp
 * @return {Boolean}
 */

var literalValueRE = /^\s?(true|false|-?[\d\.]+|'[^']*'|"[^"]*")\s?$/;

function isLiteral(exp) {
  return literalValueRE.test(exp);
}

/**
 * Check if a string starts with $ or _
 *
 * @param {String} str
 * @return {Boolean}
 */

function isReserved(str) {
  var c = (str + '').charCodeAt(0);
  return c === 0x24 || c === 0x5F;
}

/**
 * Guard text output, make sure undefined outputs
 * empty string
 *
 * @param {*} value
 * @return {String}
 */

function _toString(value) {
  return value == null ? '' : value.toString();
}

/**
 * Check and convert possible numeric strings to numbers
 * before setting back to data
 *
 * @param {*} value
 * @return {*|Number}
 */

function toNumber(value) {
  if (typeof value !== 'string') {
    return value;
  } else {
    var parsed = Number(value);
    return isNaN(parsed) ? value : parsed;
  }
}

/**
 * Convert string boolean literals into real booleans.
 *
 * @param {*} value
 * @return {*|Boolean}
 */

function toBoolean(value) {
  return value === 'true' ? true : value === 'false' ? false : value;
}

/**
 * Strip quotes from a string
 *
 * @param {String} str
 * @return {String | false}
 */

function stripQuotes(str) {
  var a = str.charCodeAt(0);
  var b = str.charCodeAt(str.length - 1);
  return a === b && (a === 0x22 || a === 0x27) ? str.slice(1, -1) : str;
}

/**
 * Camelize a hyphen-delmited string.
 *
 * @param {String} str
 * @return {String}
 */

var camelizeRE = /-(\w)/g;

function camelize(str) {
  return str.replace(camelizeRE, toUpper);
}

function toUpper(_, c) {
  return c ? c.toUpperCase() : '';
}

/**
 * Hyphenate a camelCase string.
 *
 * @param {String} str
 * @return {String}
 */

var hyphenateRE = /([a-z\d])([A-Z])/g;

function hyphenate(str) {
  return str.replace(hyphenateRE, '$1-$2').toLowerCase();
}

/**
 * Converts hyphen/underscore/slash delimitered names into
 * camelized classNames.
 *
 * e.g. my-component => MyComponent
 *      some_else    => SomeElse
 *      some/comp    => SomeComp
 *
 * @param {String} str
 * @return {String}
 */

var classifyRE = /(?:^|[-_\/])(\w)/g;

function classify(str) {
  return str.replace(classifyRE, toUpper);
}

/**
 * Simple bind, faster than native
 *
 * @param {Function} fn
 * @param {Object} ctx
 * @return {Function}
 */

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.
 *
 * @param {Array-like} list
 * @param {Number} [start] - start index
 * @return {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.
 *
 * @param {Object} to
 * @param {Object} from
 */

function extend(to, from) {
  var keys = Object.keys(from);
  var i = keys.length;
  while (i--) {
    to[keys[i]] = from[keys[i]];
  }
  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.
 *
 * @param {*} obj
 * @return {Boolean}
 */

function isObject(obj) {
  return obj !== null && typeof obj === 'object';
}

/**
 * Strict object type check. Only returns true
 * for plain JavaScript objects.
 *
 * @param {*} obj
 * @return {Boolean}
 */

var toString = Object.prototype.toString;
var OBJECT_STRING = '[object Object]';

function isPlainObject(obj) {
  return toString.call(obj) === OBJECT_STRING;
}

/**
 * Array type check.
 *
 * @param {*} obj
 * @return {Boolean}
 */

var isArray = Array.isArray;

/**
 * Define a property.
 *
 * @param {Object} obj
 * @param {String} key
 * @param {*} val
 * @param {Boolean} [enumerable]
 */

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

/**
 * Debounce a function so it only gets called after the
 * input stops arriving after the given wait period.
 *
 * @param {Function} func
 * @param {Number} wait
 * @return {Function} - the debounced function
 */

function _debounce(func, wait) {
  var timeout, args, context, timestamp, result;
  var later = function later() {
    var last = Date.now() - timestamp;
    if (last < wait && last >= 0) {
      timeout = setTimeout(later, wait - last);
    } else {
      timeout = null;
      result = func.apply(context, args);
      if (!timeout) context = args = null;
    }
  };
  return function () {
    context = this;
    args = arguments;
    timestamp = Date.now();
    if (!timeout) {
      timeout = setTimeout(later, wait);
    }
    return result;
  };
}

/**
 * Manual indexOf because it's slightly faster than
 * native.
 *
 * @param {Array} arr
 * @param {*} obj
 */

function indexOf(arr, obj) {
  var i = arr.length;
  while (i--) {
    if (arr[i] === obj) return i;
  }
  return -1;
}

/**
 * Make a cancellable version of an async callback.
 *
 * @param {Function} fn
 * @return {Function}
 */

function cancellable(fn) {
  var cb = function cb() {
    if (!cb.cancelled) {
      return fn.apply(this, arguments);
    }
  };
  cb.cancel = function () {
    cb.cancelled = true;
  };
  return cb;
}

/**
 * Check if two values are loosely equal - that is,
 * if they are plain objects, do they have the same shape?
 *
 * @param {*} a
 * @param {*} b
 * @return {Boolean}
 */

function looseEqual(a, b) {
  /* eslint-disable eqeqeq */
  return a == b || (isObject(a) && isObject(b) ? JSON.stringify(a) === JSON.stringify(b) : false);
  /* eslint-enable eqeqeq */
}

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 isIE9 = UA && UA.indexOf('msie 9.0') > 0;
var isAndroid = UA && UA.indexOf('android') > 0;

var transitionProp = undefined;
var transitionEndEvent = undefined;
var animationProp = undefined;
var animationEndEvent = undefined;

// Transition property/event sniffing
if (inBrowser && !isIE9) {
  var isWebkitTrans = window.ontransitionend === undefined && window.onwebkittransitionend !== undefined;
  var isWebkitAnim = window.onanimationend === undefined && window.onwebkitanimationend !== undefined;
  transitionProp = isWebkitTrans ? 'WebkitTransition' : 'transition';
  transitionEndEvent = isWebkitTrans ? 'webkitTransitionEnd' : 'transitionend';
  animationProp = isWebkitAnim ? 'WebkitAnimation' : 'animation';
  animationEndEvent = isWebkitAnim ? 'webkitAnimationEnd' : 'animationend';
}

/**
 * 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;
  function nextTickHandler() {
    pending = false;
    var copies = callbacks.slice(0);
    callbacks = [];
    for (var i = 0; i < copies.length; i++) {
      copies[i]();
    }
  }

  /* istanbul ignore if */
  if (typeof MutationObserver !== 'undefined') {
    var counter = 1;
    var observer = new MutationObserver(nextTickHandler);
    var textNode = document.createTextNode(counter);
    observer.observe(textNode, {
      characterData: true
    });
    timerFunc = function () {
      counter = (counter + 1) % 2;
      textNode.data = 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);
  };
})();

function Cache(limit) {
  this.size = 0;
  this.limit = limit;
  this.head = this.tail = undefined;
  this._keymap = Object.create(null);
}

var p = Cache.prototype;

/**
 * Put <value> into the cache associated with <key>.
 * Returns the entry which was removed to make room for
 * the new entry. Otherwise undefined is returned.
 * (i.e. if there was enough room already).
 *
 * @param {String} key
 * @param {*} value
 * @return {Entry|undefined}
 */

p.put = function (key, value) {
  var removed;
  if (this.size === this.limit) {
    removed = this.shift();
  }

  var entry = this.get(key, true);
  if (!entry) {
    entry = {
      key: key
    };
    this._keymap[key] = entry;
    if (this.tail) {
      this.tail.newer = entry;
      entry.older = this.tail;
    } else {
      this.head = entry;
    }
    this.tail = entry;
    this.size++;
  }
  entry.value = value;

  return removed;
};

/**
 * Purge the least recently used (oldest) entry from the
 * cache. Returns the removed entry or undefined if the
 * cache was empty.
 */

p.shift = function () {
  var entry = this.head;
  if (entry) {
    this.head = this.head.newer;
    this.head.older = undefined;
    entry.newer = entry.older = undefined;
    this._keymap[entry.key] = undefined;
    this.size--;
  }
  return entry;
};

/**
 * Get and register recent use of <key>. Returns the value
 * associated with <key> or undefined if not in cache.
 *
 * @param {String} key
 * @param {Boolean} returnEntry
 * @return {Entry|*}
 */

p.get = function (key, returnEntry) {
  var entry = this._keymap[key];
  if (entry === undefined) return;
  if (entry === this.tail) {
    return returnEntry ? entry : entry.value;
  }
  // HEAD--------------TAIL
  //   <.older   .newer>
  //  <--- add direction --
  //   A  B  C  <D>  E
  if (entry.newer) {
    if (entry === this.head) {
      this.head = entry.newer;
    }
    entry.newer.older = entry.older; // C <-- E.
  }
  if (entry.older) {
    entry.older.newer = entry.newer; // C. --> E
  }
  entry.newer = undefined; // D --x
  entry.older = this.tail; // D. --> E
  if (this.tail) {
    this.tail.newer = entry; // E. <-- D
  }
  this.tail = entry;
  return returnEntry ? entry : entry.value;
};

var cache$1 = new Cache(1000);
var filterTokenRE = /[^\s'"]+|'[^']*'|"[^"]*"/g;
var reservedArgRE = /^in$|^-?\d+/;

/**
 * Parser state
 */

var str;
var dir;
var c;
var prev;
var i;
var l;
var lastFilterIndex;
var inSingle;
var inDouble;
var curly;
var square;
var paren;
/**
 * Push a filter to the current directive object
 */

function pushFilter() {
  var exp = str.slice(lastFilterIndex, i).trim();
  var filter;
  if (exp) {
    filter = {};
    var tokens = exp.match(filterTokenRE);
    filter.name = tokens[0];
    if (tokens.length > 1) {
      filter.args = tokens.slice(1).map(processFilterArg);
    }
  }
  if (filter) {
    (dir.filters = dir.filters || []).push(filter);
  }
  lastFilterIndex = i + 1;
}

/**
 * Check if an argument is dynamic and strip quotes.
 *
 * @param {String} arg
 * @return {Object}
 */

function processFilterArg(arg) {
  if (reservedArgRE.test(arg)) {
    return {
      value: toNumber(arg),
      dynamic: false
    };
  } else {
    var stripped = stripQuotes(arg);
    var dynamic = stripped === arg;
    return {
      value: dynamic ? arg : stripped,
      dynamic: dynamic
    };
  }
}

/**
 * Parse a directive value and extract the expression
 * and its filters into a descriptor.
 *
 * Example:
 *
 * "a + 1 | uppercase" will yield:
 * {
 *   expression: 'a + 1',
 *   filters: [
 *     { name: 'uppercase', args: null }
 *   ]
 * }
 *
 * @param {String} str
 * @return {Object}
 */

function parseDirective(s) {
  var hit = cache$1.get(s);
  if (hit) {
    return hit;
  }

  // reset parser state
  str = s;
  inSingle = inDouble = false;
  curly = square = paren = 0;
  lastFilterIndex = 0;
  dir = {};

  for (i = 0, l = str.length; i < l; i++) {
    prev = c;
    c = str.charCodeAt(i);
    if (inSingle) {
      // check single quote
      if (c === 0x27 && prev !== 0x5C) inSingle = !inSingle;
    } else if (inDouble) {
      // check double quote
      if (c === 0x22 && prev !== 0x5C) inDouble = !inDouble;
    } else if (c === 0x7C && // pipe
    str.charCodeAt(i + 1) !== 0x7C && str.charCodeAt(i - 1) !== 0x7C) {
      if (dir.expression == null) {
        // first filter, end of expression
        lastFilterIndex = i + 1;
        dir.expression = str.slice(0, i).trim();
      } else {
        // already has filter
        pushFilter();
      }
    } else {
      switch (c) {
        case 0x22:
          inDouble = true;break; // "
        case 0x27:
          inSingle = true;break; // '
        case 0x28:
          paren++;break; // (
        case 0x29:
          paren--;break; // )
        case 0x5B:
          square++;break; // [
        case 0x5D:
          square--;break; // ]
        case 0x7B:
          curly++;break; // {
        case 0x7D:
          curly--;break; // }
      }
    }
  }

  if (dir.expression == null) {
    dir.expression = str.slice(0, i).trim();
  } else if (lastFilterIndex !== 0) {
    pushFilter();
  }

  cache$1.put(s, dir);
  return dir;
}

var directive = Object.freeze({
  parseDirective: parseDirective
});

var regexEscapeRE = /[-.*+?^${}()|[\]\/\\]/g;
var cache = undefined;
var tagRE = undefined;
var htmlRE = undefined;
/**
 * Escape a string so it can be used in a RegExp
 * constructor.
 *
 * @param {String} str
 */

function escapeRegex(str) {
  return str.replace(regexEscapeRE, '\\$&');
}

function compileRegex() {
  var open = escapeRegex(config.delimiters[0]);
  var close = escapeRegex(config.delimiters[1]);
  var unsafeOpen = escapeRegex(config.unsafeDelimiters[0]);
  var unsafeClose = escapeRegex(config.unsafeDelimiters[1]);
  tagRE = new RegExp(unsafeOpen + '(.+?)' + unsafeClose + '|' + open + '(.+?)' + close, 'g');
  htmlRE = new RegExp('^' + unsafeOpen + '.*' + unsafeClose + '$');
  // reset cache
  cache = new Cache(1000);
}

/**
 * Parse a template text string into an array of tokens.
 *
 * @param {String} text
 * @return {Array<Object> | null}
 *               - {String} type
 *               - {String} value
 *               - {Boolean} [html]
 *               - {Boolean} [oneTime]
 */

function parseText(text) {
  if (!cache) {
    compileRegex();
  }
  var hit = cache.get(text);
  if (hit) {
    return hit;
  }
  text = text.replace(/\n/g, '');
  if (!tagRE.test(text)) {
    return null;
  }
  var tokens = [];
  var lastIndex = tagRE.lastIndex = 0;
  var match, index, html, value, first, oneTime;
  /* eslint-disable no-cond-assign */
  while (match = tagRE.exec(text)) {
    /* eslint-enable no-cond-assign */
    index = match.index;
    // push text token
    if (index > lastIndex) {
      tokens.push({
        value: text.slice(lastIndex, index)
      });
    }
    // tag token
    html = htmlRE.test(match[0]);
    value = html ? match[1] : match[2];
    first = value.charCodeAt(0);
    oneTime = first === 42; // *
    value = oneTime ? value.slice(1) : value;
    tokens.push({
      tag: true,
      value: value.trim(),
      html: html,
      oneTime: oneTime
    });
    lastIndex = index + match[0].length;
  }
  if (lastIndex < text.length) {
    tokens.push({
      value: text.slice(lastIndex)
    });
  }
  cache.put(text, tokens);
  return tokens;
}

/**
 * Format a list of tokens into an expression.
 * e.g. tokens parsed from 'a {{b}} c' can be serialized
 * into one single expression as '"a " + b + " c"'.
 *
 * @param {Array} tokens
 * @param {Vue} [vm]
 * @return {String}
 */

function tokensToExp(tokens, vm) {
  if (tokens.length > 1) {
    return tokens.map(function (token) {
      return formatToken(token, vm);
    }).join('+');
  } else {
    return formatToken(tokens[0], vm, true);
  }
}

/**
 * Format a single token.
 *
 * @param {Object} token
 * @param {Vue} [vm]
 * @param {Boolean} [single]
 * @return {String}
 */

function formatToken(token, vm, single) {
  return token.tag ? token.oneTime && vm ? '"' + vm.$eval(token.value) + '"' : inlineFilters(token.value, single) : '"' + token.value + '"';
}

/**
 * For an attribute with multiple interpolation tags,
 * e.g. attr="some-{{thing | filter}}", in order to combine
 * the whole thing into a single watchable expression, we
 * have to inline those filters. This function does exactly
 * that. This is a bit hacky but it avoids heavy changes
 * to directive parser and watcher mechanism.
 *
 * @param {String} exp
 * @param {Boolean} single
 * @return {String}
 */

var filterRE = /[^|]\|[^|]/;
function inlineFilters(exp, single) {
  if (!filterRE.test(exp)) {
    return single ? exp : '(' + exp + ')';
  } else {
    var dir = parseDirective(exp);
    if (!dir.filters) {
      return '(' + exp + ')';
    } else {
      return 'this._applyFilters(' + dir.expression + // value
      ',null,' + // oldValue (null for read)
      JSON.stringify(dir.filters) + // filter descriptors
      ',false)'; // write?
    }
  }
}

var text = Object.freeze({
  compileRegex: compileRegex,
  parseText: parseText,
  tokensToExp: tokensToExp
});

var delimiters = ['{{', '}}'];
var unsafeDelimiters = ['{{{', '}}}'];

var config = Object.defineProperties({

  /**
   * Whether to print debug messages.
   * Also enables stack trace for warnings.
   *
   * @type {Boolean}
   */

  debug: false,

  /**
   * Whether to suppress warnings.
   *
   * @type {Boolean}
   */

  silent: false,

  /**
   * Whether to use async rendering.
   */

  async: true,

  /**
   * Whether to warn against errors caught when evaluating
   * expressions.
   */

  warnExpressionErrors: true,

  /**
   * Whether to allow devtools inspection.
   * Disabled by default in production builds.
   */

  devtools: process.env.NODE_ENV !== 'production',

  /**
   * Internal flag to indicate the delimiters have been
   * changed.
   *
   * @type {Boolean}
   */

  _delimitersChanged: true,

  /**
   * List of asset types that a component can own.
   *
   * @type {Array}
   */

  _assetTypes: ['component', 'directive', 'elementDirective', 'filter', 'transition', 'partial'],

  /**
   * prop binding modes
   */

  _propBindingModes: {
    ONE_WAY: 0,
    TWO_WAY: 1,
    ONE_TIME: 2
  },

  /**
   * Max circular updates allowed in a batcher flush cycle.
   */

  _maxUpdateCount: 100

}, {
  delimiters: { /**
                 * Interpolation delimiters. Changing these would trigger
                 * the text parser to re-compile the regular expressions.
                 *
                 * @type {Array<String>}
                 */

    get: function get() {
      return delimiters;
    },
    set: function set(val) {
      delimiters = val;
      compileRegex();
    },
    configurable: true,
    enumerable: true
  },
  unsafeDelimiters: {
    get: function get() {
      return unsafeDelimiters;
    },
    set: function set(val) {
      unsafeDelimiters = val;
      compileRegex();
    },
    configurable: true,
    enumerable: true
  }
});

var warn = undefined;

if (process.env.NODE_ENV !== 'production') {
  (function () {
    var hasConsole = typeof console !== 'undefined';
    warn = function (msg, e) {
      if (hasConsole && (!config.silent || config.debug)) {
        console.warn('[Vue warn]: ' + msg);
        /* istanbul ignore if */
        if (config.debug) {
          if (e) {
            throw e;
          } else {
            console.warn(new Error('Warning Stack Trace').stack);
          }
        }
      }
    };
  })();
}

/**
 * Append with transition.
 *
 * @param {Element} el
 * @param {Element} target
 * @param {Vue} vm
 * @param {Function} [cb]
 */

function appendWithTransition(el, target, vm, cb) {
  applyTransition(el, 1, function () {
    target.appendChild(el);
  }, vm, cb);
}

/**
 * InsertBefore with transition.
 *
 * @param {Element} el
 * @param {Element} target
 * @param {Vue} vm
 * @param {Function} [cb]
 */

function beforeWithTransition(el, target, vm, cb) {
  applyTransition(el, 1, function () {
    before(el, target);
  }, vm, cb);
}

/**
 * Remove with transition.
 *
 * @param {Element} el
 * @param {Vue} vm
 * @param {Function} [cb]
 */

function removeWithTransition(el, vm, cb) {
  applyTransition(el, -1, function () {
    remove(el);
  }, vm, cb);
}

/**
 * Apply transitions with an operation callback.
 *
 * @param {Element} el
 * @param {Number} direction
 *                  1: enter
 *                 -1: leave
 * @param {Function} op - the actual DOM operation
 * @param {Vue} vm
 * @param {Function} [cb]
 */

function applyTransition(el, direction, op, vm, cb) {
  var transition = el.__v_trans;
  if (!transition ||
  // skip if there are no js hooks and CSS transition is
  // not supported
  !transition.hooks && !transitionEndEvent ||
  // skip transitions for initial compile
  !vm._isCompiled ||
  // if the vm is being manipulated by a parent directive
  // during the parent's compilation phase, skip the
  // animation.
  vm.$parent && !vm.$parent._isCompiled) {
    op();
    if (cb) cb();
    return;
  }
  var action = direction > 0 ? 'enter' : 'leave';
  transition[action](op, cb);
}

var transition = Object.freeze({
  appendWithTransition: appendWithTransition,
  beforeWithTransition: beforeWithTransition,
  removeWithTransition: removeWithTransition,
  applyTransition: applyTransition
});

/**
 * Query an element selector if it's not an element already.
 *
 * @param {String|Element} el
 * @return {Element}
 */

function query(el) {
  if (typeof el === 'string') {
    var selector = el;
    el = document.querySelector(el);
    if (!el) {
      process.env.NODE_ENV !== 'production' && warn('Cannot find element: ' + selector);
    }
  }
  return el;
}

/**
 * Check if a node is in the document.
 * Note: document.documentElement.contains should work here
 * but always returns false for comment nodes in phantomjs,
 * making unit tests difficult. This is fixed by doing the
 * contains() check on the node's parentNode instead of
 * the node itself.
 *
 * @param {Node} node
 * @return {Boolean}
 */

function inDoc(node) {
  var doc = document.documentElement;
  var parent = node && node.parentNode;
  return doc === node || doc === parent || !!(parent && parent.nodeType === 1 && doc.contains(parent));
}

/**
 * Get and remove an attribute from a node.
 *
 * @param {Node} node
 * @param {String} _attr
 */

function getAttr(node, _attr) {
  var val = node.getAttribute(_attr);
  if (val !== null) {
    node.removeAttribute(_attr);
  }
  return val;
}

/**
 * Get an attribute with colon or v-bind: prefix.
 *
 * @param {Node} node
 * @param {String} name
 * @return {String|null}
 */

function getBindAttr(node, name) {
  var val = getAttr(node, ':' + name);
  if (val === null) {
    val = getAttr(node, 'v-bind:' + name);
  }
  return val;
}

/**
 * Check the presence of a bind attribute.
 *
 * @param {Node} node
 * @param {String} name
 * @return {Boolean}
 */

function hasBindAttr(node, name) {
  return node.hasAttribute(name) || node.hasAttribute(':' + name) || node.hasAttribute('v-bind:' + name);
}

/**
 * Insert el before target
 *
 * @param {Element} el
 * @param {Element} target
 */

function before(el, target) {
  target.parentNode.insertBefore(el, target);
}

/**
 * Insert el after target
 *
 * @param {Element} el
 * @param {Element} target
 */

function after(el, target) {
  if (target.nextSibling) {
    before(el, target.nextSibling);
  } else {
    target.parentNode.appendChild(el);
  }
}

/**
 * Remove el from DOM
 *
 * @param {Element} el
 */

function remove(el) {
  el.parentNode.removeChild(el);
}

/**
 * Prepend el to target
 *
 * @param {Element} el
 * @param {Element} target
 */

function prepend(el, target) {
  if (target.firstChild) {
    before(el, target.firstChild);
  } else {
    target.appendChild(el);
  }
}

/**
 * Replace target with el
 *
 * @param {Element} target
 * @param {Element} el
 */

function replace(target, el) {
  var parent = target.parentNode;
  if (parent) {
    parent.replaceChild(el, target);
  }
}

/**
 * Add event listener shorthand.
 *
 * @param {Element} el
 * @param {String} event
 * @param {Function} cb
 * @param {Boolean} [useCapture]
 */

function on(el, event, cb, useCapture) {
  el.addEventListener(event, cb, useCapture);
}

/**
 * Remove event listener shorthand.
 *
 * @param {Element} el
 * @param {String} event
 * @param {Function} cb
 */

function off(el, event, cb) {
  el.removeEventListener(event, cb);
}

/**
 * In IE9, setAttribute('class') will result in empty class
 * if the element also has the :class attribute; However in
 * PhantomJS, setting `className` does not work on SVG elements...
 * So we have to do a conditional check here.
 *
 * @param {Element} el
 * @param {String} cls
 */

function setClass(el, cls) {
  /* istanbul ignore if */
  if (isIE9 && !/svg$/.test(el.namespaceURI)) {
    el.className = cls;
  } else {
    el.setAttribute('class', cls);
  }
}

/**
 * Add class with compatibility for IE & SVG
 *
 * @param {Element} el
 * @param {String} cls
 */

function addClass(el, cls) {
  if (el.classList) {
    el.classList.add(cls);
  } else {
    var cur = ' ' + (el.getAttribute('class') || '') + ' ';
    if (cur.indexOf(' ' + cls + ' ') < 0) {
      setClass(el, (cur + cls).trim());
    }
  }
}

/**
 * Remove class with compatibility for IE & SVG
 *
 * @param {Element} el
 * @param {String} cls
 */

function removeClass(el, cls) {
  if (el.classList) {
    el.classList.remove(cls);
  } else {
    var cur = ' ' + (el.getAttribute('class') || '') + ' ';
    var tar = ' ' + cls + ' ';
    while (cur.indexOf(tar) >= 0) {
      cur = cur.replace(tar, ' ');
    }
    setClass(el, cur.trim());
  }
  if (!el.className) {
    el.removeAttribute('class');
  }
}

/**
 * Extract raw content inside an element into a temporary
 * container div
 *
 * @param {Element} el
 * @param {Boolean} asFragment
 * @return {Element|DocumentFragment}
 */

function extractContent(el, asFragment) {
  var child;
  var rawContent;
  /* istanbul ignore if */
  if (isTemplate(el) && isFragment(el.content)) {
    el = el.content;
  }
  if (el.hasChildNodes()) {
    trimNode(el);
    rawContent = asFragment ? document.createDocumentFragment() : document.createElement('div');
    /* eslint-disable no-cond-assign */
    while (child = el.firstChild) {
      /* eslint-enable no-cond-assign */
      rawContent.appendChild(child);
    }
  }
  return rawContent;
}

/**
 * Trim possible empty head/tail text and comment
 * nodes inside a parent.
 *
 * @param {Node} node
 */

function trimNode(node) {
  var child;
  /* eslint-disable no-sequences */
  while ((child = node.firstChild, isTrimmable(child))) {
    node.removeChild(child);
  }
  while ((child = node.lastChild, isTrimmable(child))) {
    node.removeChild(child);
  }
  /* eslint-enable no-sequences */
}

function isTrimmable(node) {
  return node && (node.nodeType === 3 && !node.data.trim() || node.nodeType === 8);
}

/**
 * Check if an element is a template tag.
 * Note if the template appears inside an SVG its tagName
 * will be in lowercase.
 *
 * @param {Element} el
 */

function isTemplate(el) {
  return el.tagName && el.tagName.toLowerCase() === 'template';
}

/**
 * Create an "anchor" for performing dom insertion/removals.
 * This is used in a number of scenarios:
 * - fragment instance
 * - v-html
 * - v-if
 * - v-for
 * - component
 *
 * @param {String} content
 * @param {Boolean} persist - IE trashes empty textNodes on
 *                            cloneNode(true), so in certain
 *                            cases the anchor needs to be
 *                            non-empty to be persisted in
 *                            templates.
 * @return {Comment|Text}
 */

function createAnchor(content, persist) {
  var anchor = config.debug ? document.createComment(content) : document.createTextNode(persist ? ' ' : '');
  anchor.__v_anchor = true;
  return anchor;
}

/**
 * Find a component ref attribute that starts with $.
 *
 * @param {Element} node
 * @return {String|undefined}
 */

var refRE = /^v-ref:/;

function findRef(node) {
  if (node.hasAttributes()) {
    var attrs = node.attributes;
    for (var i = 0, l = attrs.length; i < l; i++) {
      var name = attrs[i].name;
      if (refRE.test(name)) {
        return camelize(name.replace(refRE, ''));
      }
    }
  }
}

/**
 * Map a function to a range of nodes .
 *
 * @param {Node} node
 * @param {Node} end
 * @param {Function} op
 */

function mapNodeRange(node, end, op) {
  var next;
  while (node !== end) {
    next = node.nextSibling;
    op(node);
    node = next;
  }
  op(end);
}

/**
 * Remove a range of nodes with transition, store
 * the nodes in a fragment with correct ordering,
 * and call callback when done.
 *
 * @param {Node} start
 * @param {Node} end
 * @param {Vue} vm
 * @param {DocumentFragment} frag
 * @param {Function} cb
 */

function removeNodeRange(start, end, vm, frag, cb) {
  var done = false;
  var removed = 0;
  var nodes = [];
  mapNodeRange(start, end, function (node) {
    if (node === end) done = true;
    nodes.push(node);
    removeWithTransition(node, vm, onRemoved);
  });
  function onRemoved() {
    removed++;
    if (done && removed >= nodes.length) {
      for (var i = 0; i < nodes.length; i++) {
        frag.appendChild(nodes[i]);
      }
      cb && cb();
    }
  }
}

/**
 * Check if a node is a DocumentFragment.
 *
 * @param {Node} node
 * @return {Boolean}
 */

function isFragment(node) {
  return node && node.nodeType === 11;
}

/**
 * Get outerHTML of elements, taking care
 * of SVG elements in IE as well.
 *
 * @param {Element} el
 * @return {String}
 */

function getOuterHTML(el) {
  if (el.outerHTML) {
    return el.outerHTML;
  } else {
    var container = document.createElement('div');
    container.appendChild(el.cloneNode(true));
    return container.innerHTML;
  }
}

var uid$1 = 0;

/**
 * A dep is an observable that can have multiple
 * directives subscribing to it.
 *
 * @constructor
 */
function Dep() {
  this.id = uid$1++;
  this.subs = [];
}

// the current target watcher being evaluated.
// this is globally unique because there could be only one
// watcher being evaluated at any time.
Dep.target = null;

/**
 * Add a directive subscriber.
 *
 * @param {Directive} sub
 */

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

/**
 * Remove a directive subscriber.
 *
 * @param {Directive} sub
 */

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

/**
 * Add self as a dependency to the target watcher.
 */

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

/**
 * Notify all subscribers of a new value.
 */

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

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;
    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;
  });
});

/**
 * Swap the element at the given index with a new value
 * and emits corresponding event.
 *
 * @param {Number} index
 * @param {*} val
 * @return {*} - replaced element
 */

def(arrayProto, '$set', function $set(index, val) {
  if (index >= this.length) {
    this.length = Number(index) + 1;
  }
  return this.splice(index, 1, val)[0];
});

/**
 * Convenience method to remove the element at given index.
 *
 * @param {Number} index
 * @param {*} val
 */

def(arrayProto, '$remove', function $remove(item) {
  /* istanbul ignore if */
  if (!this.length) return;
  var index = indexOf(this, item);
  if (index > -1) {
    return this.splice(index, 1);
  }
});

var arrayKeys = Object.getOwnPropertyNames(arrayMethods);

/**
 * 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.
 *
 * @param {Array|Object} value
 * @constructor
 */

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

// Instance methods

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

Observer.prototype.walk = function (obj) {
  var keys = Object.keys(obj);
  for (var i = 0, l = keys.length; i < l; i++) {
    this.convert(keys[i], obj[keys[i]]);
  }
};

/**
 * Observe a list of Array items.
 *
 * @param {Array} items
 */

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

/**
 * Convert a property into getter/setter so we can emit
 * the events when the property is accessed/changed.
 *
 * @param {String} key
 * @param {*} val
 */

Observer.prototype.convert = function (key, val) {
  defineReactive(this.value, key, val);
};

/**
 * Add an owner vm, so that when $set/$delete mutations
 * happen we can notify owner vms to proxy the keys and
 * digest the watchers. This is only called when the object
 * is observed as an instance's root $data.
 *
 * @param {Vue} vm
 */

Observer.prototype.addVm = function (vm) {
  (this.vms || (this.vms = [])).push(vm);
};

/**
 * Remove an owner vm. This is called when the object is
 * swapped out as an instance's $data object.
 *
 * @param {Vue} vm
 */

Observer.prototype.removeVm = function (vm) {
  this.vms.$remove(vm);
};

// helpers

/**
 * Augment an target Object or Array by intercepting
 * the prototype chain using __proto__
 *
 * @param {Object|Array} target
 * @param {Object} 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.
 *
 * @param {Object|Array} target
 * @param {Object} proto
 */

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.
 *
 * @param {*} value
 * @param {Vue} [vm]
 * @return {Observer|undefined}
 * @static
 */

function observe(value, vm) {
  if (!value || typeof value !== 'object') {
    return;
  }
  var ob;
  if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
    ob = value.__ob__;
  } else if ((isArray(value) || isPlainObject(value)) && Object.isExtensible(value) && !value._isVue) {
    ob = new Observer(value);
  }
  if (ob && vm) {
    ob.addVm(vm);
  }
  return ob;
}

/**
 * Define a reactive property on an Object.
 *
 * @param {Object} obj
 * @param {String} key
 * @param {*} val
 * @param {Boolean} doNotObserve
 */

function defineReactive(obj, key, val, doNotObserve) {
  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;

  // if doNotObserve is true, only use the child value observer
  // if it already exists, and do not attempt to create it.
  // this allows freezing a large object from the root and
  // avoid unnecessary observation inside v-for fragments.
  var childOb = doNotObserve ? isObject(val) && val.__ob__ : 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 (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 (setter) {
        setter.call(obj, newVal);
      } else {
        val = newVal;
      }
      childOb = doNotObserve ? isObject(newVal) && newVal.__ob__ : observe(newVal);
      dep.notify();
    }
  });
}

var commonTagRE = /^(div|p|span|img|a|b|i|br|ul|ol|li|h1|h2|h3|h4|h5|h6|code|pre|table|th|td|tr|form|label|input|select|option|nav|article|section|header|footer)$/i;
var reservedTagRE = /^(slot|partial|component)$/i;

var isUnknownElement = undefined;
if (process.env.NODE_ENV !== 'production') {
  isUnknownElement = function (el, tag) {
    if (tag.indexOf('-') > -1) {
      // http://stackoverflow.com/a/28210364/1070244
      return el.constructor === window.HTMLUnknownElement || el.constructor === window.HTMLElement;
    } else {
      return (/HTMLUnknownElement/.test(el.toString()) &&
        // Chrome returns unknown for several HTML5 elements.
        // https://code.google.com/p/chromium/issues/detail?id=540526
        !/^(data|time|rtc|rb)$/.test(tag)
      );
    }
  };
}

/**
 * Check if an element is a component, if yes return its
 * component id.
 *
 * @param {Element} el
 * @param {Object} options
 * @return {Object|undefined}
 */

function checkComponentAttr(el, options) {
  var tag = el.tagName.toLowerCase();
  var hasAttrs = el.hasAttributes();
  if (!commonTagRE.test(tag) && !reservedTagRE.test(tag)) {
    if (resolveAsset(options, 'components', tag)) {
      return { id: tag };
    } else {
      var is = hasAttrs && getIsBinding(el);
      if (is) {
        return is;
      } else if (process.env.NODE_ENV !== 'production') {
        var expectedTag = options._componentNameMap && options._componentNameMap[tag];
        if (expectedTag) {
          warn('Unknown custom element: <' + tag + '> - ' + 'did you mean <' + expectedTag + '>? ' + 'HTML is case-insensitive, remember to use kebab-case in templates.');
        } else if (isUnknownElement(el, tag)) {
          warn('Unknown custom element: <' + tag + '> - did you ' + 'register the component correctly? For recursive components, ' + 'make sure to provide the "name" option.');
        }
      }
    }
  } else if (hasAttrs) {
    return getIsBinding(el);
  }
}

/**
 * Get "is" binding from an element.
 *
 * @param {Element} el
 * @return {Object|undefined}
 */

function getIsBinding(el) {
  // dynamic syntax
  var exp = getAttr(el, 'is');
  if (exp != null) {
    return { id: exp };
  } else {
    exp = getBindAttr(el, 'is');
    if (exp != null) {
      return { id: exp, dynamic: true };
    }
  }
}

/**
 * Set a prop's initial value on a vm and its data object.
 *
 * @param {Vue} vm
 * @param {Object} prop
 * @param {*} value
 */

function initProp(vm, prop, value) {
  var key = prop.path;
  value = coerceProp(prop, value);
  if (value === undefined) {
    value = getPropDefaultValue(vm, prop.options);
  }
  if (assertProp(prop, value)) {
    defineReactive(vm, key, value, true /* doNotObserve */);
  }
}

/**
 * Get the default value of a prop.
 *
 * @param {Vue} vm
 * @param {Object} options
 * @return {*}
 */

function getPropDefaultValue(vm, options) {
  // no default, return undefined
  if (!hasOwn(options, 'default')) {
    // absent boolean value defaults to false
    return options.type === Boolean ? false : undefined;
  }
  var def = options['default'];
  // warn against non-factory defaults for Object & Array
  if (isObject(def)) {
    process.env.NODE_ENV !== 'production' && warn('Object/Array as default prop values will be shared ' + 'across multiple instances. Use a factory function ' + 'to return the default value instead.');
  }
  // call factory function for non-Function types
  return typeof def === 'function' && options.type !== Function ? def.call(vm) : def;
}

/**
 * Assert whether a prop is valid.
 *
 * @param {Object} prop
 * @param {*} value
 */

function assertProp(prop, value) {
  if (!prop.options.required && ( // non-required
  prop.raw === null || // abscent
  value == null) // null or undefined
  ) {
      return true;
    }
  var options = prop.options;
  var type = options.type;
  var valid = true;
  var expectedType;
  if (type) {
    if (type === String) {
      expectedType = 'string';
      valid = typeof value === expectedType;
    } else if (type === Number) {
      expectedType = 'number';
      valid = typeof value === 'number';
    } else if (type === Boolean) {
      expectedType = 'boolean';
      valid = typeof value === 'boolean';
    } else if (type === Function) {
      expectedType = 'function';
      valid = typeof value === 'function';
    } else if (type === Object) {
      expectedType = 'object';
      valid = isPlainObject(value);
    } else if (type === Array) {
      expectedType = 'array';
      valid = isArray(value);
    } else {
      valid = value instanceof type;
    }
  }
  if (!valid) {
    process.env.NODE_ENV !== 'production' && warn('Invalid prop: type check failed for ' + prop.path + '="' + prop.raw + '".' + ' Expected ' + formatType(expectedType) + ', got ' + formatValue(value) + '.');
    return false;
  }
  var validator = options.validator;
  if (validator) {
    if (!validator(value)) {
      process.env.NODE_ENV !== 'production' && warn('Invalid prop: custom validator check failed for ' + prop.path + '="' + prop.raw + '"');
      return false;
    }
  }
  return true;
}

/**
 * Force parsing value with coerce option.
 *
 * @param {*} value
 * @param {Object} options
 * @return {*}
 */

function coerceProp(prop, value) {
  var coerce = prop.options.coerce;
  if (!coerce) {
    return value;
  }
  // coerce is a function
  return coerce(value);
}

function formatType(val) {
  return val ? val.charAt(0).toUpperCase() + val.slice(1) : 'custom type';
}

function formatValue(val) {
  return Object.prototype.toString.call(val).slice(8, -1);
}

/**
 * Option overwriting strategies are functions that handle
 * how to merge a parent option value and a child option
 * value into the final value.
 *
 * All strategy functions follow the same signature:
 *
 * @param {*} parentVal
 * @param {*} childVal
 * @param {Vue} [vm]
 */

var strats = config.optionMergeStrategies = Object.create(null);

/**
 * Helper that recursively merges two data objects together.
 */

function mergeData(to, from) {
  var key, toVal, fromVal;
  for (key in from) {
    toVal = to[key];
    fromVal = from[key];
    if (!hasOwn(to, key)) {
      set(to, key, fromVal);
    } else if (isObject(toVal) && isObject(fromVal)) {
      mergeData(toVal, fromVal);
    }
  }
  return to;
}

/**
 * Data
 */

strats.data = function (parentVal, childVal, vm) {
  if (!vm) {
    // in a Vue.extend merge, both should be functions
    if (!childVal) {
      return parentVal;
    }
    if (typeof childVal !== 'function') {
      process.env.NODE_ENV !== 'production' && warn('The "data" option should be a function ' + 'that returns a per-instance value in component ' + 'definitions.');
      return parentVal;
    }
    if (!parentVal) {
      return childVal;
    }
    // when parentVal & childVal are both present,
    // we need to return a function that returns the
    // merged result of both functions... no need to
    // check if parentVal is a function here because
    // it has to be a function to pass previous merges.
    return function mergedDataFn() {
      return mergeData(childVal.call(this), parentVal.call(this));
    };
  } else if (parentVal || childVal) {
    return function mergedInstanceDataFn() {
      // instance merge
      var instanceData = typeof childVal === 'function' ? childVal.call(vm) : childVal;
      var defaultData = typeof parentVal === 'function' ? parentVal.call(vm) : undefined;
      if (instanceData) {
        return mergeData(instanceData, defaultData);
      } else {
        return defaultData;
      }
    };
  }
};

/**
 * El
 */

strats.el = function (parentVal, childVal, vm) {
  if (!vm && childVal && typeof childVal !== 'function') {
    process.env.NODE_ENV !== 'production' && warn('The "el" option should be a function ' + 'that returns a per-instance value in component ' + 'definitions.');
    return;
  }
  var ret = childVal || parentVal;
  // invoke the element factory if this is instance merge
  return vm && typeof ret === 'function' ? ret.call(vm) : ret;
};

/**
 * Hooks and param attributes are merged as arrays.
 */

strats.init = strats.created = strats.ready = strats.attached = strats.detached = strats.beforeCompile = strats.compiled = strats.beforeDestroy = strats.destroyed = strats.activate = function (parentVal, childVal) {
  return childVal ? parentVal ? parentVal.concat(childVal) : isArray(childVal) ? childVal : [childVal] : parentVal;
};

/**
 * 0.11 deprecation warning
 */

strats.paramAttributes = function () {
  /* istanbul ignore next */
  process.env.NODE_ENV !== 'production' && warn('"paramAttributes" option has been deprecated in 0.12. ' + 'Use "props" instead.');
};

/**
 * Assets
 *
 * When a vm is present (instance creation), we need to do
 * a three-way merge between constructor options, instance
 * options and parent options.
 */

function mergeAssets(parentVal, childVal) {
  var res = Object.create(parentVal);
  return childVal ? extend(res, guardArrayAssets(childVal)) : res;
}

config._assetTypes.forEach(function (type) {
  strats[type + 's'] = mergeAssets;
});

/**
 * Events & Watchers.
 *
 * Events & watchers hashes should not overwrite one
 * another, so we merge them as arrays.
 */

strats.watch = strats.events = function (parentVal, childVal) {
  if (!childVal) return parentVal;
  if (!parentVal) return childVal;
  var ret = {};
  extend(ret, parentVal);
  for (var key in childVal) {
    var parent = ret[key];
    var child = childVal[key];
    if (parent && !isArray(parent)) {
      parent = [parent];
    }
    ret[key] = parent ? parent.concat(child) : [child];
  }
  return ret;
};

/**
 * Other object hashes.
 */

strats.props = strats.methods = strats.computed = function (parentVal, childVal) {
  if (!childVal) return parentVal;
  if (!parentVal) return childVal;
  var ret = Object.create(null);
  extend(ret, parentVal);
  extend(ret, childVal);
  return ret;
};

/**
 * Default strategy.
 */

var defaultStrat = function defaultStrat(parentVal, childVal) {
  return childVal === undefined ? parentVal : childVal;
};

/**
 * Make sure component options get converted to actual
 * constructors.
 *
 * @param {Object} options
 */

function guardComponents(options) {
  if (options.components) {
    var components = options.components = guardArrayAssets(options.components);
    var ids = Object.keys(components);
    var def;
    if (process.env.NODE_ENV !== 'production') {
      var map = options._componentNameMap = {};
    }
    for (var i = 0, l = ids.length; i < l; i++) {
      var key = ids[i];
      if (commonTagRE.test(key) || reservedTagRE.test(key)) {
        process.env.NODE_ENV !== 'production' && warn('Do not use built-in or reserved HTML elements as component ' + 'id: ' + key);
        continue;
      }
      // record a all lowercase <-> kebab-case mapping for
      // possible custom element case error warning
      if (process.env.NODE_ENV !== 'production') {
        map[key.replace(/-/g, '').toLowerCase()] = hyphenate(key);
      }