Vue2.x学习笔记

# 项目代码

前言

这里的 vue 项目是指通过vue/cli创建的项目，通过 webpack 运行的项目；根组件配置 render，vue 源码不带编译函数，xx.vue文件由 webpack 插件vue-loader编译成xx.js文件，template 被编译为 render 函数，这里只考虑首次加载的情况。

  • main.js
import App from "./App.vue"
import config from "./config"
import ui from "./ui"
Vue.use(ui)
Vue.use(config)
new Vue({
  render(h) {
    return h(<App />)
  },
}).$mount("#app")
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  • app.vue
<template>{{ a }}</template>
<script>
export default {
  data() {
    return {
      a: "1",
    }
  },
  props: {
    a: {
      type: String,
    },
  },
  provide: {
    b: this,
  },
  inject: {
    b: "b",
  },
  beforeCreate() {},
  created() {},
  beforeMount() {},
  mounted() {},
  methods: {},
}
</script>
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# 1.Vue 引入

在main.js中，使用 vue

import Vue from "vue"
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vue 在内部会组装成一个类输出使用

# 2.使用前

vue先引入后在 vue 上加载各种插件

# 2.1 Vue.use

  • 我们在项目中使用Vue.use添加插件时，走的就是这个逻辑，它会去寻找插件的install方法，然后执行内部逻辑

  • /src/vue/src/core/global-api/use.ts

export function initUse(Vue: GlobalAPI) {
  Vue.use = function (plugin: Function | any) {
    const installedPlugins =
      this._installedPlugins || (this._installedPlugins = [])
    if (installedPlugins.indexOf(plugin) > -1) {
      return this
    }

    // additional parameters
    const args = toArray(arguments, 1)
    args.unshift(this)
    if (isFunction(plugin.install)) {
      plugin.install.apply(plugin, args)
    } else if (isFunction(plugin)) {
      plugin.apply(null, args)
    }
    installedPlugins.push(plugin)
    return this
  }
}
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vue 内部上会维持一个_installedPlugins数组，存储上面安装过的插件，相同的插件只安装一次

# 2.2 Vue.component

添加component以及directive

  • /src/vue/src/core/global-api/assets.ts
export function initAssetRegisters(Vue: GlobalAPI) {
  /**
   * Create asset registration methods.
   */
  ASSET_TYPES.forEach(type => {
    // @ts-expect-error function is not exact same type
    Vue[type] = function (
      id: string,
      definition?: Function | Object
    ): Function | Object | void {
      if (!definition) {
        return this.options[type + 's'][id]
      } else {
        /* istanbul ignore if */
        if (__DEV__ && type === 'component') {
          validateComponentName(id)
        }
        if (type === 'component' && isPlainObject(definition)) {
          // @ts-expect-error
          definition.name = definition.name || id
          definition = this.options._base.extend(definition)
        }
        if (type === 'directive' && isFunction(definition)) {
          definition = { bind: definition, update: definition }
        }
        this.options[type + 's'][id] = definition
        return definition
      }
    }
  })
}
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# 2.3 Vue.directive

添加component以及directive

  • /src/vue/src/core/global-api/assets.ts
export function initAssetRegisters(Vue: GlobalAPI) {
  /**
   * Create asset registration methods.
   */
  ASSET_TYPES.forEach(type => {
    // @ts-expect-error function is not exact same type
    Vue[type] = function (
      id: string,
      definition?: Function | Object
    ): Function | Object | void {
      if (!definition) {
        return this.options[type + 's'][id]
      } else {
        /* istanbul ignore if */
        if (__DEV__ && type === 'component') {
          validateComponentName(id)
        }
        if (type === 'component' && isPlainObject(definition)) {
          // @ts-expect-error
          definition.name = definition.name || id
          definition = this.options._base.extend(definition)
        }
        if (type === 'directive' && isFunction(definition)) {
          definition = { bind: definition, update: definition }
        }
        this.options[type + 's'][id] = definition
        return definition
      }
    }
  })
}
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# 2.4 Vue.mixin

  • 我们在项目中使用Vue.mixin复用某些属性，走的就是这个逻辑，它会将相关数据与目标的options在内部进行合并，从而达到混入的效果

  • /src/vue/src/core/global-api/mixin.ts

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

实例化vue生成一个根组件，通过$mount挂载到某个 dom 节点上

# 3.1 _init

  • main.js
const app = new Vue({
  render: (h) => h(App),
})
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在 _init中完成组件数据的初始化处理

# 3.2 $mount

子组件逻辑走完了，父组件就开始挂载了

  • main.js
app.$mount("#app")
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在 $mount中完成一次挂载处理，此处主要是为了处理template模板代码，即将其编译为 render 函数形式，由于main.js中通过 render 函数生成标签，这里进入二次挂载

# 4.App.vue

App.vue在父组件中引用，一部分逻辑会先在父组件中处理，父组件派发更新时才进入子组件内部逻辑

# 4.1 父组件h(App)

  • main.js
render: (h) => h(App)
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  • 源码部分
vnode = render.call(vm._renderProxy, vm.$createElement)
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这里的h就是 vue 内部的 render 函数，既vm.$createElement

vm.$createElement = (a, b, c, d) => createElement(vm, a, b, c, d, true)
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  • /src/vue/src/core/vdom/create-element.ts
















 

export function createElement(
  context: Component,
  tag: any,
  data: any,
  children: any,
  normalizationType: any,
  alwaysNormalize: boolean
): VNode | Array<VNode> {
  if (isArray(data) || isPrimitive(data)) {
    normalizationType = children
    children = data
    data = undefined
  }
  if (isTrue(alwaysNormalize)) {
    normalizationType = ALWAYS_NORMALIZE
  }
  return _createElement(context, tag, data, children, normalizationType)
}
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  • /src/vue/src/core/vdom/create-element.ts










































































 




 















export function _createElement(
  context: Component,
  tag?: string | Component | Function | Object,
  data?: VNodeData,
  children?: any,
  normalizationType?: number
): VNode | Array<VNode> {
  if (isDef(data) && isDef((data as any).__ob__)) {
    __DEV__ &&
      warn(
        `Avoid using observed data object as vnode data: ${JSON.stringify(
          data
        )}\n` + 'Always create fresh vnode data objects in each render!',
        context
      )
    return createEmptyVNode()
  }
  // object syntax in v-bind
  if (isDef(data) && isDef(data.is)) {
    tag = data.is
  }
  if (!tag) {
    // in case of component :is set to falsy value
    return createEmptyVNode()
  }
  // warn against non-primitive key
  if (__DEV__ && isDef(data) && isDef(data.key) && !isPrimitive(data.key)) {
    warn(
      'Avoid using non-primitive value as key, ' +
        'use string/number value instead.',
      context
    )
  }
  // support single function children as default scoped slot
  if (isArray(children) && isFunction(children[0])) {
    data = data || {}
    data.scopedSlots = { default: children[0] }
    children.length = 0
  }
  if (normalizationType === ALWAYS_NORMALIZE) {
    children = normalizeChildren(children)
  } else if (normalizationType === SIMPLE_NORMALIZE) {
    children = simpleNormalizeChildren(children)
  }
  let vnode, ns
  if (typeof tag === 'string') {
    let Ctor
    ns = (context.$vnode && context.$vnode.ns) || config.getTagNamespace(tag)
    if (config.isReservedTag(tag)) {
      // platform built-in elements
      if (
        __DEV__ &&
        isDef(data) &&
        isDef(data.nativeOn) &&
        data.tag !== 'component'
      ) {
        warn(
          `The .native modifier for v-on is only valid on components but it was used on <${tag}>.`,
          context
        )
      }
      vnode = new VNode(
        config.parsePlatformTagName(tag),
        data,
        children,
        undefined,
        undefined,
        context
      )
    } else if (
      (!data || !data.pre) &&
      isDef((Ctor = resolveAsset(context.$options, 'components', tag)))
    ) {
      // component
      vnode = createComponent(Ctor, data, context, children, tag)
    } else {
      // unknown or unlisted namespaced elements
      // check at runtime because it may get assigned a namespace when its
      // parent normalizes children
      vnode = new VNode(tag, data, children, undefined, undefined, context)
    }
  } else {
    // direct component options / constructor
    vnode = createComponent(tag as any, data, context, children)
  }
  if (isArray(vnode)) {
    return vnode
  } else if (isDef(vnode)) {
    if (isDef(ns)) applyNS(vnode, ns)
    if (isDef(data)) registerDeepBindings(data)
    return vnode
  } else {
    return createEmptyVNode()
  }
}
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在这里 render 函数将标签转为 vnode

这里主要看两种 vnode：普通标签 vnode、组件 vnode

  • 由于App.vue为组件，所有这里走组件 vnode 的逻辑，通过createComponent创建组件 vnode

  • /src/vue/src/core/vdom/create-component.ts
















 










































































 



















export function createComponent(
  Ctor: typeof Component | Function | ComponentOptions | void,
  data: VNodeData | undefined,
  context: Component,
  children?: Array<VNode>,
  tag?: string
): VNode | Array<VNode> | void {
  if (isUndef(Ctor)) {
    return
  }

  const baseCtor = context.$options._base

  // plain options object: turn it into a constructor
  if (isObject(Ctor)) {
    Ctor = baseCtor.extend(Ctor as typeof Component)
  }

  // if at this stage it's not a constructor or an async component factory,
  // reject.
  if (typeof Ctor !== 'function') {
    if (__DEV__) {
      warn(`Invalid Component definition: ${String(Ctor)}`, context)
    }
    return
  }

  // async component
  let asyncFactory
  // @ts-expect-error
  if (isUndef(Ctor.cid)) {
    asyncFactory = Ctor
    Ctor = resolveAsyncComponent(asyncFactory, baseCtor)
    if (Ctor === undefined) {
      // return a placeholder node for async component, which is rendered
      // as a comment node but preserves all the raw information for the node.
      // the information will be used for async server-rendering and hydration.
      return createAsyncPlaceholder(asyncFactory, data, context, children, tag)
    }
  }

  data = data || {}

  // resolve constructor options in case global mixins are applied after
  // component constructor creation
  resolveConstructorOptions(Ctor as typeof Component)

  // transform component v-model data into props & events
  if (isDef(data.model)) {
    // @ts-expect-error
    transformModel(Ctor.options, data)
  }

  // extract props
  // @ts-expect-error
  const propsData = extractPropsFromVNodeData(data, Ctor, tag)

  // functional component
  // @ts-expect-error
  if (isTrue(Ctor.options.functional)) {
    return createFunctionalComponent(
      Ctor as typeof Component,
      propsData,
      data,
      context,
      children
    )
  }

  // extract listeners, since these needs to be treated as
  // child component listeners instead of DOM listeners
  const listeners = data.on
  // replace with listeners with .native modifier
  // so it gets processed during parent component patch.
  data.on = data.nativeOn

  // @ts-expect-error
  if (isTrue(Ctor.options.abstract)) {
    // abstract components do not keep anything
    // other than props & listeners & slot

    // work around flow
    const slot = data.slot
    data = {}
    if (slot) {
      data.slot = slot
    }
  }

  // install component management hooks onto the placeholder node
  installComponentHooks(data)

  // return a placeholder vnode
  // @ts-expect-error
  const name = getComponentName(Ctor.options) || tag
  const vnode = new VNode(
    // @ts-expect-error
    `vue-component-${Ctor.cid}${name ? `-${name}` : ''}`,
    data,
    undefined,
    undefined,
    undefined,
    context,
    // @ts-expect-error
    { Ctor, propsData, listeners, tag, children },
    asyncFactory
  )

  return vnode
}
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App.vue通过import App from './App.vue'方式引入使用，所以是同步引入，编译后是一个对象

installComponentHooks为组件提供不同的生命周期

  • /src/vue/src/core/global-api/extend.ts




























 












































export function initExtend(Vue: GlobalAPI) {
  /**
   * Each instance constructor, including Vue, has a unique
   * cid. This enables us to create wrapped "child
   * constructors" for prototypal inheritance and cache them.
   */
  Vue.cid = 0
  let cid = 1

  /**
   * Class inheritance
   */
  Vue.extend = function (extendOptions: any): typeof Component {
    extendOptions = extendOptions || {}
    const Super = this
    const SuperId = Super.cid
    const cachedCtors = extendOptions._Ctor || (extendOptions._Ctor = {})
    if (cachedCtors[SuperId]) {
      return cachedCtors[SuperId]
    }

    const name =
      getComponentName(extendOptions) || getComponentName(Super.options)
    if (__DEV__ && name) {
      validateComponentName(name)
    }

    const Sub = function VueComponent(this: any, options: any) {
      this._init(options)
    } as unknown as typeof Component
    Sub.prototype = Object.create(Super.prototype)
    Sub.prototype.constructor = Sub
    Sub.cid = cid++
    Sub.options = mergeOptions(Super.options, extendOptions)
    Sub['super'] = Super

    // For props and computed properties, we define the proxy getters on
    // the Vue instances at extension time, on the extended prototype. This
    // avoids Object.defineProperty calls for each instance created.
    if (Sub.options.props) {
      initProps(Sub)
    }
    if (Sub.options.computed) {
      initComputed(Sub)
    }

    // allow further extension/mixin/plugin usage
    Sub.extend = Super.extend
    Sub.mixin = Super.mixin
    Sub.use = Super.use

    // create asset registers, so extended classes
    // can have their private assets too.
    ASSET_TYPES.forEach(function (type) {
      Sub[type] = Super[type]
    })
    // enable recursive self-lookup
    if (name) {
      Sub.options.components[name] = Sub
    }

    // keep a reference to the super options at extension time.
    // later at instantiation we can check if Super's options have
    // been updated.
    Sub.superOptions = Super.options
    Sub.extendOptions = extendOptions
    Sub.sealedOptions = extend({}, Sub.options)

    // cache constructor
    cachedCtors[SuperId] = Sub
    return Sub
  }
}
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可以看到，子组件通过 extend继承了一些方法和属性（如：_init）

# 4.2 父组件vm._update

  • /src/vue/src/core/instance/lifecycle.ts










 


























Vue.prototype._update = function (vnode: VNode, hydrating?: boolean) {
  const vm: Component = this
  const prevEl = vm.$el
  const prevVnode = vm._vnode
  const restoreActiveInstance = setActiveInstance(vm)
  vm._vnode = vnode
  // Vue.prototype.__patch__ is injected in entry points
  // based on the rendering backend used.
  if (!prevVnode) {
    // initial render
    vm.$el = vm.__patch__(vm.$el, vnode, hydrating, false /* removeOnly */)
  } else {
    // updates
    vm.$el = vm.__patch__(prevVnode, vnode)
  }
  restoreActiveInstance()
  // update __vue__ reference
  if (prevEl) {
    prevEl.__vue__ = null
  }
  if (vm.$el) {
    vm.$el.__vue__ = vm
  }
  // if parent is an HOC, update its $el as well
  let wrapper: Component | undefined = vm
  while (
    wrapper &&
    wrapper.$vnode &&
    wrapper.$parent &&
    wrapper.$vnode === wrapper.$parent._vnode
  ) {
    wrapper.$parent.$el = wrapper.$el
    wrapper = wrapper.$parent
  }
  // updated hook is called by the scheduler to ensure that children are
  // updated in a parent's updated hook.
}
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组件 vnode 通过vm.__patch__初始化

  • /src/vue/src/platforms/web/runtime/index.ts
Vue.prototype.__patch__ = inBrowser ? patch : noop

兼容处理

  • /src/vue/src/platforms/web/runtime/patch.ts
export const patch: Function = createPatchFunction({ nodeOps, modules })
  • /src/vue/src/core/vdom/patch.ts



















































 
 
 
 
 
 
 
 
 








































 


return function patch(oldVnode, vnode, hydrating, removeOnly) {
  if (isUndef(vnode)) {
    if (isDef(oldVnode)) invokeDestroyHook(oldVnode)
    return
  }

  let isInitialPatch = false
  const insertedVnodeQueue: any[] = []

  if (isUndef(oldVnode)) {
    // empty mount (likely as component), create new root element
    isInitialPatch = true
    createElm(vnode, insertedVnodeQueue)
  } else {
    const isRealElement = isDef(oldVnode.nodeType)
    if (!isRealElement && sameVnode(oldVnode, vnode)) {
      // patch existing root node
      patchVnode(oldVnode, vnode, insertedVnodeQueue, null, null, removeOnly)
    } else {
      if (isRealElement) {
        // mounting to a real element
        // check if this is server-rendered content and if we can perform
        // a successful hydration.
        if (oldVnode.nodeType === 1 && oldVnode.hasAttribute(SSR_ATTR)) {
          oldVnode.removeAttribute(SSR_ATTR)
          hydrating = true
        }
        if (isTrue(hydrating)) {
          if (hydrate(oldVnode, vnode, insertedVnodeQueue)) {
            invokeInsertHook(vnode, insertedVnodeQueue, true)
            return oldVnode
          } else if (__DEV__) {
            warn(
              'The client-side rendered virtual DOM tree is not matching ' +
                'server-rendered content. This is likely caused by incorrect ' +
                'HTML markup, for example nesting block-level elements inside ' +
                '<p>, or missing <tbody>. Bailing hydration and performing ' +
                'full client-side render.'
            )
          }
        }
        // either not server-rendered, or hydration failed.
        // create an empty node and replace it
        oldVnode = emptyNodeAt(oldVnode)
      }

      // replacing existing element
      const oldElm = oldVnode.elm
      const parentElm = nodeOps.parentNode(oldElm)

      // create new node
      createElm(
        vnode,
        insertedVnodeQueue,
        // extremely rare edge case: do not insert if old element is in a
        // leaving transition. Only happens when combining transition +
        // keep-alive + HOCs. (#4590)
        oldElm._leaveCb ? null : parentElm,
        nodeOps.nextSibling(oldElm)
      )

      // update parent placeholder node element, recursively
      if (isDef(vnode.parent)) {
        let ancestor = vnode.parent
        const patchable = isPatchable(vnode)
        while (ancestor) {
          for (let i = 0; i < cbs.destroy.length; ++i) {
            cbs.destroy[i](ancestor)
          }
          ancestor.elm = vnode.elm
          if (patchable) {
            for (let i = 0; i < cbs.create.length; ++i) {
              cbs.create[i](emptyNode, ancestor)
            }
            // #6513
            // invoke insert hooks that may have been merged by create hooks.
            // e.g. for directives that uses the "inserted" hook.
            const insert = ancestor.data.hook.insert
            if (insert.merged) {
              // start at index 1 to avoid re-invoking component mounted hook
              for (let i = 1; i < insert.fns.length; i++) {
                insert.fns[i]()
              }
            }
          } else {
            registerRef(ancestor)
          }
          ancestor = ancestor.parent
        }
      }

      // destroy old node
      if (isDef(parentElm)) {
        removeVnodes([oldVnode], 0, 0)
      } else if (isDef(oldVnode.tag)) {
        invokeDestroyHook(oldVnode)
      }
    }
  }

  invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch)
  return vnode.elm
}
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首次加载，没有老节点，直接新创建组件

invokeInsertHook重新执行组件的生命周期

  • /src/vue/src/core/vdom/patch.ts



















 













































function createElm(
  vnode,
  insertedVnodeQueue,
  parentElm?: any,
  refElm?: any,
  nested?: any,
  ownerArray?: any,
  index?: any
) {
  if (isDef(vnode.elm) && isDef(ownerArray)) {
    // This vnode was used in a previous render!
    // now it's used as a new node, overwriting its elm would cause
    // potential patch errors down the road when it's used as an insertion
    // reference node. Instead, we clone the node on-demand before creating
    // associated DOM element for it.
    vnode = ownerArray[index] = cloneVNode(vnode)
  }

  vnode.isRootInsert = !nested // for transition enter check
  if (createComponent(vnode, insertedVnodeQueue, parentElm, refElm)) {
    return
  }

  const data = vnode.data
  const children = vnode.children
  const tag = vnode.tag
  if (isDef(tag)) {
    if (__DEV__) {
      if (data && data.pre) {
        creatingElmInVPre++
      }
      if (isUnknownElement(vnode, creatingElmInVPre)) {
        warn(
          'Unknown custom element: <' +
            tag +
            '> - did you ' +
            'register the component correctly? For recursive components, ' +
            'make sure to provide the "name" option.',
          vnode.context
        )
      }
    }

    vnode.elm = vnode.ns
      ? nodeOps.createElementNS(vnode.ns, tag)
      : nodeOps.createElement(tag, vnode)
    setScope(vnode)

    createChildren(vnode, children, insertedVnodeQueue)
    if (isDef(data)) {
      invokeCreateHooks(vnode, insertedVnodeQueue)
    }
    insert(parentElm, vnode.elm, refElm)

    if (__DEV__ && data && data.pre) {
      creatingElmInVPre--
    }
  } else if (isTrue(vnode.isComment)) {
    vnode.elm = nodeOps.createComment(vnode.text)
    insert(parentElm, vnode.elm, refElm)
  } else {
    vnode.elm = nodeOps.createTextNode(vnode.text)
    insert(parentElm, vnode.elm, refElm)
  }
}
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由于是组件 vnode 类型，走这里

  • /src/vue/src/core/vdom/patch.ts





 















function createComponent(vnode, insertedVnodeQueue, parentElm, refElm) {
  let i = vnode.data
  if (isDef(i)) {
    const isReactivated = isDef(vnode.componentInstance) && i.keepAlive
    if (isDef((i = i.hook)) && isDef((i = i.init))) {
      i(vnode, false /* hydrating */)
    }
    // after calling the init hook, if the vnode is a child component
    // it should've created a child instance and mounted it. the child
    // component also has set the placeholder vnode's elm.
    // in that case we can just return the element and be done.
    if (isDef(vnode.componentInstance)) {
      initComponent(vnode, insertedVnodeQueue)
      insert(parentElm, vnode.elm, refElm)
      if (isTrue(isReactivated)) {
        reactivateComponent(vnode, insertedVnodeQueue, parentElm, refElm)
      }
      return true
    }
  }
}
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installComponentHooks内执行组件自身的生命周期init

  • /src/vue/src/core/vdom/create-component.ts
function installComponentHooks(data: VNodeData) {
  const hooks = data.hook || (data.hook = {})
  for (let i = 0; i < hooksToMerge.length; i++) {
    const key = hooksToMerge[i]
    const existing = hooks[key]
    const toMerge = componentVNodeHooks[key]
    // @ts-expect-error
    if (existing !== toMerge && !(existing && existing._merged)) {
      hooks[key] = existing ? mergeHook(toMerge, existing) : toMerge
    }
  }
}
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  • /src/vue/src/core/vdom/create-component.ts











 
 
 
 
 














































const componentVNodeHooks = {
  init(vnode: VNodeWithData, hydrating: boolean): boolean | void {
    if (
      vnode.componentInstance &&
      !vnode.componentInstance._isDestroyed &&
      vnode.data.keepAlive
    ) {
      // kept-alive components, treat as a patch
      const mountedNode: any = vnode // work around flow
      componentVNodeHooks.prepatch(mountedNode, mountedNode)
    } else {
      const child = (vnode.componentInstance = createComponentInstanceForVnode(
        vnode,
        activeInstance
      ))
      child.$mount(hydrating ? vnode.elm : undefined, hydrating)
    }
  },

  prepatch(oldVnode: MountedComponentVNode, vnode: MountedComponentVNode) {
    const options = vnode.componentOptions
    const child = (vnode.componentInstance = oldVnode.componentInstance)
    updateChildComponent(
      child,
      options.propsData, // updated props
      options.listeners, // updated listeners
      vnode, // new parent vnode
      options.children // new children
    )
  },

  insert(vnode: MountedComponentVNode) {
    const { context, componentInstance } = vnode
    if (!componentInstance._isMounted) {
      componentInstance._isMounted = true
      callHook(componentInstance, 'mounted')
    }
    if (vnode.data.keepAlive) {
      if (context._isMounted) {
        // vue-router#1212
        // During updates, a kept-alive component's child components may
        // change, so directly walking the tree here may call activated hooks
        // on incorrect children. Instead we push them into a queue which will
        // be processed after the whole patch process ended.
        queueActivatedComponent(componentInstance)
      } else {
        activateChildComponent(componentInstance, true /* direct */)
      }
    }
  },

  destroy(vnode: MountedComponentVNode) {
    const { componentInstance } = vnode
    if (!componentInstance._isDestroyed) {
      if (!vnode.data.keepAlive) {
        componentInstance.$destroy()
      } else {
        deactivateChildComponent(componentInstance, true /* direct */)
      }
    }
  }
}
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createComponentInstanceForVnode实例化子组件

child.$mount将子组件挂载到父组件上

至此进入子组件自身代码逻辑

# 4.3 _init

  • /src/vue/src/core/vdom/create-component.ts

















 

export function createComponentInstanceForVnode(
  // we know it's MountedComponentVNode but flow doesn't
  vnode: any,
  // activeInstance in lifecycle state
  parent?: any
): Component {
  const options: InternalComponentOptions = {
    _isComponent: true,
    _parentVnode: vnode,
    parent
  }
  // check inline-template render functions
  const inlineTemplate = vnode.data.inlineTemplate
  if (isDef(inlineTemplate)) {
    options.render = inlineTemplate.render
    options.staticRenderFns = inlineTemplate.staticRenderFns
  }
  return new vnode.componentOptions.Ctor(options)
}
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相当于new Vue,前面子组件通过继承，获得了 this._init，这里new后实例化后执行，流程和父组件this._init一致，在 _init中完成组件数据的初始化处理

# 4.4 $mount

这里的$mount和是通过child.$mount挂载的，流程和父组件$mount基本一致，生命周期mounted不是走这里的逻辑，而是通过invokeInsertHook来执行的

  • /src/vue/src/core/vdom/patch.ts







 



function invokeInsertHook(vnode, queue, initial) {
  // delay insert hooks for component root nodes, invoke them after the
  // element is really inserted
  if (isTrue(initial) && isDef(vnode.parent)) {
    vnode.parent.data.pendingInsert = queue
  } else {
    for (let i = 0; i < queue.length; ++i) {
      queue[i].data.hook.insert(queue[i])
    }
  }
}
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调用组件上的生命周期insert来实现

  • /src/vue/src/core/vdom/create-component.ts



































 


























const componentVNodeHooks = {
  init(vnode: VNodeWithData, hydrating: boolean): boolean | void {
    if (
      vnode.componentInstance &&
      !vnode.componentInstance._isDestroyed &&
      vnode.data.keepAlive
    ) {
      // kept-alive components, treat as a patch
      const mountedNode: any = vnode // work around flow
      componentVNodeHooks.prepatch(mountedNode, mountedNode)
    } else {
      const child = (vnode.componentInstance = createComponentInstanceForVnode(
        vnode,
        activeInstance
      ))
      child.$mount(hydrating ? vnode.elm : undefined, hydrating)
    }
  },

  prepatch(oldVnode: MountedComponentVNode, vnode: MountedComponentVNode) {
    const options = vnode.componentOptions
    const child = (vnode.componentInstance = oldVnode.componentInstance)
    updateChildComponent(
      child,
      options.propsData, // updated props
      options.listeners, // updated listeners
      vnode, // new parent vnode
      options.children // new children
    )
  },

  insert(vnode: MountedComponentVNode) {
    const { context, componentInstance } = vnode
    if (!componentInstance._isMounted) {
      componentInstance._isMounted = true
      callHook(componentInstance, 'mounted')
    }
    if (vnode.data.keepAlive) {
      if (context._isMounted) {
        // vue-router#1212
        // During updates, a kept-alive component's child components may
        // change, so directly walking the tree here may call activated hooks
        // on incorrect children. Instead we push them into a queue which will
        // be processed after the whole patch process ended.
        queueActivatedComponent(componentInstance)
      } else {
        activateChildComponent(componentInstance, true /* direct */)
      }
    }
  },

  destroy(vnode: MountedComponentVNode) {
    const { componentInstance } = vnode
    if (!componentInstance._isDestroyed) {
      if (!vnode.data.keepAlive) {
        componentInstance.$destroy()
      } else {
        deactivateChildComponent(componentInstance, true /* direct */)
      }
    }
  }
}
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← 首次加载(Vue 引入) →