const arrayProto = Array.prototype
 const arrayMethods = Object.create(arrayProto)
const methodsToPatch = [
  'push',
  'pop',
  'shift',
  'unshift',
  'splice',
  'sort',
  'reverse'
]

/**
 * Intercept mutating methods and emit events
 */
methodsToPatch.forEach(function (method) {  
  // cache original method
  const original = arrayProto[method]
  Object.defineProperty(arrayMethods, method, {
		value: function mutator (...args) {
    const result = original.apply(this, args)
    const ob = this.__ob__
    let inserted
    switch (method) {
      case 'push':
      case 'unshift':
        inserted = args
        break
      case 'splice':
        inserted = args.slice(2)
        break
    }
    if (inserted) {console.log("inserted")}
    // notify change
//     ob.dep.notify()
    return result
  }
	})
})