text: /* @flow */
  
  import config from '../config'
  import { initUse } from './use'
  import { initMixin } from './mixin'
  import { initExtend } from './extend'
  import { initAssetRegisters } from './assets'
  import { set, del } from '../observer/index'
  import { ASSET_TYPES } from 'shared/constants'
  import builtInComponents from '../components/index'
  
  import {
    warn,
    extend,
    nextTick,
    mergeOptions,
    defineReactive
  } from '../util/index'
  
  export function initGlobalAPI (Vue: GlobalAPI) {
    // config
    const configDef = {}
    configDef.get = () => config
    if (process.env.NODE_ENV !== 'production') {
      configDef.set = () => {
        warn(
          'Do not replace the Vue.config object, set individual fields instead.'
        )
      }
    }
    Object.defineProperty(Vue, 'config', configDef)
  
    // exposed util methods.
    // NOTE: these are not considered part of the public API - avoid relying on
    // them unless you are aware of the risk.
    Vue.util = {
      warn,
      extend,
      mergeOptions,
      defineReactive
    }
  
    Vue.set = set
    Vue.delete = del
    Vue.nextTick = nextTick
  
    Vue.options = Object.create(null)
    ASSET_TYPES.forEach(type => {
      Vue.options[type + 's'] = Object.create(null)
    })
  
    // this is used to identify the "base" constructor to extend all plain-object
    // components with in Weex's multi-instance scenarios.
    /*_base被用来标识基本构造函数（也就是Vue），以便在多场景下添加组件扩展*/
    Vue.options._base = Vue
  
    extend(Vue.options.components, builtInComponents)
  
    initUse(Vue)
    initMixin(Vue)
    initExtend(Vue)
    initAssetRegisters(Vue)
  }
  