vue中相同逻辑如何抽离

就是使用Vue.mixin方法（混入），其提供了一种非常灵活的方式，来分发 Vue 组件中的可复用功能。一个混入对象可以包含任意组件选项。当组件使用混入对象时，所有混入对象的选项将被“混合”进入该组件本身的选项。说白了就是给每个生命周期，函数等等中间加入一些公共逻辑。

//vue/src/core/global-api/mixin.js 

import { mergeOptions } from '../util/index'

export function initMixin (Vue: GlobalAPI) {
  Vue.mixin = function (mixin: Object) {
    this.options = mergeOptions(this.options, mixin)
    return this
  }
}

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//vue/src/core/util/options.js /
/**
 * Merge two option objects into a new one.
 * Core utility used in both instantiation and inheritance.
 */
export function mergeOptions (
  parent: Object,
  child: Object,
  vm?: Component
): Object {
  if (process.env.NODE_ENV !== 'production') {
    checkComponents(child)
  }

  if (typeof child === 'function') {
    child = child.options
  }

  normalizeProps(child, vm)
  normalizeInject(child, vm)
  normalizeDirectives(child)

  // Apply extends and mixins on the child options,
  // but only if it is a raw options object that isn't
  // the result of another mergeOptions call.
  // Only merged options has the _base property.
  if (!child._base) {
    if (child.extends) { //递归合并extends
      parent = mergeOptions(parent, child.extends, vm)
    }
    if (child.mixins) { //递归合并mixin
      for (let i = 0, l = child.mixins.length; i < l; i++) {
        parent = mergeOptions(parent, child.mixins[i], vm)
      }
    }
  }

  const options = {} //属性和生命周期的合并
  let key
  for (key in parent) {
    mergeField(key)
  }
  for (key in child) {
    if (!hasOwn(parent, key)) {
      mergeField(key)
    }
  }
  function mergeField (key) {
    const strat = strats[key] || defaultStrat
    options[key] = strat(parent[key], child[key], vm, key)
  }
  return options
}