vue3源码：页面渲染流程分析

通过断点调式的方式，记录了vue3页面渲染流程，和vue2选项式api的区别还是蛮大的，后续会优化整理增加注释。

一、createApp

源码路径packages/runtime-dom/src/index.ts

// packages/runtime-dom/src/index.ts
export const createApp = ((...args) => {
  console.log('args', ...args);
  const app = ensureRenderer().createApp(...args)

  if (__DEV__) { //TODO:待分析
    injectNativeTagCheck(app)
    injectCompilerOptionsCheck(app)
  }

  const { mount } = app // 解构出mount方法
  // 重写mount方法
  app.mount = (containerOrSelector: Element | ShadowRoot | string): any => {
    const container = normalizeContainer(containerOrSelector)
    if (!container) return

    const component = app._component
    if (!isFunction(component) && !component.render && !component.template) {
      // __UNSAFE__
      // Reason: potential execution of JS expressions in in-DOM template.
      // The user must make sure the in-DOM template is trusted. If it's
      // rendered by the server, the template should not contain any user data.
      component.template = container.innerHTML
      // 2.x compat check
      if (__COMPAT__ && __DEV__) {
        for (let i = 0; i < container.attributes.length; i++) {
          const attr = container.attributes[i]
          if (attr.name !== 'v-cloak' && /^(v-|:|@)/.test(attr.name)) {
            compatUtils.warnDeprecation(
              DeprecationTypes.GLOBAL_MOUNT_CONTAINER,
              null
            )
            break
          }
        }
      }
    }

    // clear content before mounting
    container.innerHTML = ''
    const proxy = mount(container, false, container instanceof SVGElement)
    if (container instanceof Element) {
      container.removeAttribute('v-cloak')
      container.setAttribute('data-v-app', '')
    }
    return proxy
  }

  return app
}) as CreateAppFunction<Element>

可以看出 createApp 方法的核心目的是创建一个 app , 创建之后重写并添加 mount 方法提供给后面链式调用。

二、app的创建过程

const app = ensureRenderer().createApp(...args)

1、ensureRenderer

路径：packages/runtime-dom/src/index.ts

function ensureRenderer() {
  return (
    renderer ||
    (renderer = createRenderer<Node, Element | ShadowRoot>(rendererOptions))
  )
}

// rendererOptions
const rendererOptions = /*#__PURE__*/ extend({ patchProp }, nodeOps)
/**
 *  rendererOptions是patchProp和nodeOps的合并，nodeOps 为真实 DOM 操作
 * /

2、createRenderer

接着我们看createRenderer方法，它的源码路径：packages/runtime-core/src/renderer.ts

export function createRenderer<
  HostNode = RendererNode,
  HostElement = RendererElement
>(options: RendererOptions<HostNode, HostElement>) {
  return baseCreateRenderer<HostNode, HostElement>(options)
}

3、baseCreateRenderer

源码路径：packages/runtime-core/src/renderer.ts

// implementation
function baseCreateRenderer(
  options: RendererOptions,
  createHydrationFns?: typeof createHydrationFunctions
): any {
    // ...
    return {
        render,
        hydrate,
        createApp: createAppAPI(render, hydrate)
    }
}

总的来说这个方法最终的目的是拿到 render , 和 createAppApi 的执行结果.

4、createAppApi

作用是生成 app 实例 注册全局 API ，这段代码和vue2创建vue实例基本一致，源码路径：packages/runtime-core/src/apiCreateApp.ts

let uid = 0

export function createAppAPI<HostElement>(
  render: RootRenderFunction<HostElement>,
  hydrate?: RootHydrateFunction
): CreateAppFunction<HostElement> {
  // createApp接收2个参数，根组件和根组件的属性
  return function createApp(rootComponent, rootProps = null) {
    if (!isFunction(rootComponent)) {
      rootComponent = extend({}, rootComponent)
    }

    if (rootProps != null && !isObject(rootProps)) {
      __DEV__ && warn(`root props passed to app.mount() must be an object.`)
      rootProps = null
    }
    // 创建一个上下文对象
    const context = createAppContext()
    const installedPlugins = new Set()

    let isMounted = false
    // 重写上下文对象的app属性
    console.log('----createAppAPI----:', rootComponent)
    const app: App = (context.app = {
      _uid: uid++,
      _component: rootComponent as ConcreteComponent,
      _props: rootProps,
      _container: null,
      _context: context,
      _instance: null,

      version,

      get config() { // 暴露的应用实例的配置
        return context.config
      },

      set config(v) {
        if (__DEV__) {
          warn(
            `app.config cannot be replaced. Modify individual options instead.`
          )
        }
      },

      use(plugin: Plugin, ...options: any[]) { // 插件的安装，可以看出，插件如果是对象，必须有install方法；如果是函数，则默认是安装方法
        if (installedPlugins.has(plugin)) {
          __DEV__ && warn(`Plugin has already been applied to target app.`)
        } else if (plugin && isFunction(plugin.install)) {
          installedPlugins.add(plugin)
          plugin.install(app, ...options)
        } else if (isFunction(plugin)) {
          installedPlugins.add(plugin)
          plugin(app, ...options)
        } else if (__DEV__) {
          warn(
            `A plugin must either be a function or an object with an "install" ` +
              `function.`
          )
        }
        return app
      },

      mixin(mixin: ComponentOptions) {
        if (__FEATURE_OPTIONS_API__) {
          if (!context.mixins.includes(mixin)) {
            context.mixins.push(mixin)
          } else if (__DEV__) {
            warn(
              'Mixin has already been applied to target app' +
                (mixin.name ? `: ${mixin.name}` : '')
            )
          }
        } else if (__DEV__) {
          warn('Mixins are only available in builds supporting Options API')
        }
        return app
      },

      component(name: string, component?: Component): any {
        if (__DEV__) {
          validateComponentName(name, context.config)
        }
        if (!component) {
          return context.components[name]
        }
        if (__DEV__ && context.components[name]) {
          warn(`Component "${name}" has already been registered in target app.`)
        }
        context.components[name] = component
        return app
      },

      directive(name: string, directive?: Directive) {
        if (__DEV__) {
          validateDirectiveName(name)
        }

        if (!directive) {
          return context.directives[name] as any
        }
        if (__DEV__ && context.directives[name]) {
          warn(`Directive "${name}" has already been registered in target app.`)
        }
        context.directives[name] = directive
        return app
      },

      mount(
        rootContainer: HostElement,
        isHydrate?: boolean,
        isSVG?: boolean
      ): any {
        if (!isMounted) {
          // #5571
          if (__DEV__ && (rootContainer as any).__vue_app__) {
            warn(
              `There is already an app instance mounted on the host container.\n` +
                ` If you want to mount another app on the same host container,` +
                ` you need to unmount the previous app by calling \`app.unmount()\` first.`
            )
          }
          const vnode = createVNode(
            rootComponent as ConcreteComponent,
            rootProps
          )
          // store app context on the root VNode.
          // this will be set on the root instance on initial mount.
          vnode.appContext = context

          // HMR root reload
          if (__DEV__) {
            context.reload = () => {
              render(cloneVNode(vnode), rootContainer, isSVG)
            }
          }

          if (isHydrate && hydrate) {
            hydrate(vnode as VNode<Node, Element>, rootContainer as any)
          } else {
            render(vnode, rootContainer, isSVG)
          }
          isMounted = true
          app._container = rootContainer
          // for devtools and telemetry
          ;(rootContainer as any).__vue_app__ = app

          if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
            app._instance = vnode.component
            devtoolsInitApp(app, version)
          }

          return getExposeProxy(vnode.component!) || vnode.component!.proxy
        } else if (__DEV__) {
          warn(
            `App has already been mounted.\n` +
              `If you want to remount the same app, move your app creation logic ` +
              `into a factory function and create fresh app instances for each ` +
              `mount - e.g. \`const createMyApp = () => createApp(App)\``
          )
        }
      },

      unmount() {
        if (isMounted) {
          render(null, app._container)
          if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
            app._instance = null
            devtoolsUnmountApp(app)
          }
          delete app._container.__vue_app__
        } else if (__DEV__) {
          warn(`Cannot unmount an app that is not mounted.`)
        }
      },

      provide(key, value) {
        if (__DEV__ && (key as string | symbol) in context.provides) {
          warn(
            `App already provides property with key "${String(key)}". ` +
              `It will be overwritten with the new value.`
          )
        }

        context.provides[key as string | symbol] = value

        return app
      },

      runWithContext(fn) {
        currentApp = app
        try {
          return fn()
        } finally {
          currentApp = null
        }
      }
    })

    if (__COMPAT__) {
      installAppCompatProperties(app, context, render)
    }

    return app
  }
}

• 首先通过createAppContext创建一个app的空的对象

export function createAppContext(): AppContext {
  return {
    app: null as any,
    config: {
      isNativeTag: NO,
      performance: false,
      globalProperties: {},
      optionMergeStrategies: {},
      errorHandler: undefined,
      warnHandler: undefined,
      compilerOptions: {}
    },
    mixins: [],
    components: {},
    directives: {},
    provides: Object.create(null),
    optionsCache: new WeakMap(),
    propsCache: new WeakMap(),
    emitsCache: new WeakMap()
  }
}

• 接着会注册插件、全局API等

• 声明了渲染用的方法mount

最后返回app实例. 到这里为止, 我们的 app 实例就创建好了，也就是const app = ensureRenderer().createApp(...args)这行代码多做的事情。 我们可以看出, vue3 的设计方式是将平台相关的操作抽离出去, 只需要关注对应平台的节点操作, 创建渲染器即可。

---

三、继续看createApp

const { mount } = app // 解构出mount方法
  // 重写mount方法
  app.mount = (containerOrSelector: Element | ShadowRoot | string): any => {
    const container = normalizeContainer(containerOrSelector)
    if (!container) return

    const component = app._component
    if (!isFunction(component) && !component.render && !component.template) {
      // __UNSAFE__
      // Reason: potential execution of JS expressions in in-DOM template.
      // The user must make sure the in-DOM template is trusted. If it's
      // rendered by the server, the template should not contain any user data.
      component.template = container.innerHTML
      // 2.x compat check
      if (__COMPAT__ && __DEV__) {
        for (let i = 0; i < container.attributes.length; i++) {
          const attr = container.attributes[i]
          if (attr.name !== 'v-cloak' && /^(v-|:|@)/.test(attr.name)) {
            compatUtils.warnDeprecation(
              DeprecationTypes.GLOBAL_MOUNT_CONTAINER,
              null
            )
            break
          }
        }
      }
    }

    // clear content before mounting
    container.innerHTML = ''
    const proxy = mount(container, false, container instanceof SVGElement)
    if (container instanceof Element) {
      container.removeAttribute('v-cloak')
      container.setAttribute('data-v-app', '')
    }
    return proxy
  }

获取到 app 实例之后, vue 把实例中的 mount 方法缓存了一下, 并且重写实例上的 mount 方法. 当我们调用 mount 时(调用的是重写之后的 mount ),最终调用的还是实例上的mount方法const proxy = mount(container, false, container instanceof SVGElement)

• 首先验证挂载元素是否合法

• 获取实例上的app._component，实际上是createApp注册的选项

• 如果注册的选项 不是 function || 没有 render 配置 || 没有 template 配置的话 , 会给 component 增加 template 属性, component.template = container.innerHTML

• 之后清空容器里的 innerHTML, container.innerHTML = ''

• 执行之前缓存的(实例中的) mount 方法, const proxy = mount(container, false, container instanceof SVGElement)

四、继续看createAppApi中的mount

源码路径packages/runtime-core/src/apiCreateApp.ts

export function createAppAPI<HostElement>(
  render: RootRenderFunction<HostElement>,
  hydrate?: RootHydrateFunction
): CreateAppFunction<HostElement> {
  // createApp接收2个参数，根组件和根组件的属性
  return function createApp(rootComponent, rootProps = null) {
    mount(
        rootContainer: HostElement, // <div id="app"></div>
        isHydrate?: boolean,
        isSVG?: boolean
      ): any {
        if (!isMounted) {
          // #5571
          if (__DEV__ && (rootContainer as any).__vue_app__) {
            warn(
              `There is already an app instance mounted on the host container.\n` +
                ` If you want to mount another app on the same host container,` +
                ` you need to unmount the previous app by calling \`app.unmount()\` first.`
            )
          }
          const vnode = createVNode(
            rootComponent as ConcreteComponent,
            rootProps
          )
          // store app context on the root VNode.
          // this will be set on the root instance on initial mount.
          // 获取到 vnode 后, 将当前实例上下文添加到 vnode
          vnode.appContext = context

          // HMR root reload
          if (__DEV__) {
            context.reload = () => {
              render(cloneVNode(vnode), rootContainer, isSVG)
            }
          }

          if (isHydrate && hydrate) {
            hydrate(vnode as VNode<Node, Element>, rootContainer as any)
          } else {
            //  调用 render 方法 (此时的 render 方法是通过创建 app 实例 时的形参传入的, 声明是在渲染器中)
            render(vnode, rootContainer, isSVG)
          }
          // render 结束后将挂载状态置为 true
          isMounted = true
          app._container = rootContainer
          // for devtools and telemetry
          ;(rootContainer as any).__vue_app__ = app

          if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
            app._instance = vnode.component
            devtoolsInitApp(app, version)
          }

          return getExposeProxy(vnode.component!) || vnode.component!.proxy
        } else if (__DEV__) {
          warn(
            `App has already been mounted.\n` +
              `If you want to remount the same app, move your app creation logic ` +
              `into a factory function and create fresh app instances for each ` +
              `mount - e.g. \`const createMyApp = () => createApp(App)\``
          )
        }
      },
  }
}

• createVNode

export const createVNode = (
  __DEV__ ? createVNodeWithArgsTransform : _createVNode
) as typeof _createVNode

function _createVNode(
  type: VNodeTypes | ClassComponent | typeof NULL_DYNAMIC_COMPONENT,
  props: (Data & VNodeProps) | null = null,
  children: unknown = null,
  patchFlag: number = 0,
  dynamicProps: string[] | null = null,
  isBlockNode = false
): VNode {
  if (!type || type === NULL_DYNAMIC_COMPONENT) {
    if (__DEV__ && !type) {
      warn(`Invalid vnode type when creating vnode: ${type}.`)
    }
    type = Comment
  }

  if (isVNode(type)) {
    // createVNode receiving an existing vnode. This happens in cases like
    // <component :is="vnode"/>
    // #2078 make sure to merge refs during the clone instead of overwriting it
    const cloned = cloneVNode(type, props, true /* mergeRef: true */)
    if (children) {
      normalizeChildren(cloned, children)
    }
    if (isBlockTreeEnabled > 0 && !isBlockNode && currentBlock) {
      if (cloned.shapeFlag & ShapeFlags.COMPONENT) {
        currentBlock[currentBlock.indexOf(type)] = cloned
      } else {
        currentBlock.push(cloned)
      }
    }
    cloned.patchFlag |= PatchFlags.BAIL
    return cloned
  }

  // class component normalization.
  if (isClassComponent(type)) {
    type = type.__vccOpts
  }

  // 2.x async/functional component compat
  if (__COMPAT__) {
    type = convertLegacyComponent(type, currentRenderingInstance)
  }

  // class & style normalization.
  if (props) {
    // for reactive or proxy objects, we need to clone it to enable mutation.
    props = guardReactiveProps(props)!
    let { class: klass, style } = props
    if (klass && !isString(klass)) {
      props.class = normalizeClass(klass)
    }
    if (isObject(style)) {
      // reactive state objects need to be cloned since they are likely to be
      // mutated
      if (isProxy(style) && !isArray(style)) {
        style = extend({}, style)
      }
      props.style = normalizeStyle(style)
    }
  }

  // encode the vnode type information into a bitmap
  const shapeFlag = isString(type)
    ? ShapeFlags.ELEMENT
    : __FEATURE_SUSPENSE__ && isSuspense(type)
    ? ShapeFlags.SUSPENSE
    : isTeleport(type)
    ? ShapeFlags.TELEPORT
    : isObject(type)
    ? ShapeFlags.STATEFUL_COMPONENT
    : isFunction(type)
    ? ShapeFlags.FUNCTIONAL_COMPONENT
    : 0

  if (__DEV__ && shapeFlag & ShapeFlags.STATEFUL_COMPONENT && isProxy(type)) {
    type = toRaw(type)
    warn(
      `Vue received a Component which was made a reactive object. This can ` +
        `lead to unnecessary performance overhead, and should be avoided by ` +
        `marking the component with \`markRaw\` or using \`shallowRef\` ` +
        `instead of \`ref\`.`,
      `\nComponent that was made reactive: `,
      type
    )
  }

  return createBaseVNode(
    type,
    props,
    children,
    patchFlag,
    dynamicProps,
    shapeFlag,
    isBlockNode,
    true
  )
}

• normalizeChildren

作用是对children进行规范（使children 变成了一个类型为 VNode 的 Array）

• createBaseVNode 真正创建vNode的方法

function createBaseVNode(
  type: VNodeTypes | ClassComponent | typeof NULL_DYNAMIC_COMPONENT,
  props: (Data & VNodeProps) | null = null,
  children: unknown = null,
  patchFlag = 0,
  dynamicProps: string[] | null = null,
  shapeFlag = type === Fragment ? 0 : ShapeFlags.ELEMENT,
  isBlockNode = false,
  needFullChildrenNormalization = false
) {
  const vnode = {
    __v_isVNode: true,
    __v_skip: true,
    type,
    props,
    key: props && normalizeKey(props),
    ref: props && normalizeRef(props),
    scopeId: currentScopeId,
    slotScopeIds: null,
    children,
    component: null,
    suspense: null,
    ssContent: null,
    ssFallback: null,
    dirs: null,
    transition: null,
    el: null,
    anchor: null,
    target: null,
    targetAnchor: null,
    staticCount: 0,
    shapeFlag,
    patchFlag,
    dynamicProps,
    dynamicChildren: null,
    appContext: null,
    ctx: currentRenderingInstance
  } as VNode

  if (needFullChildrenNormalization) {
    normalizeChildren(vnode, children)
    // normalize suspense children
    if (__FEATURE_SUSPENSE__ && shapeFlag & ShapeFlags.SUSPENSE) {
      ;(type as typeof SuspenseImpl).normalize(vnode)
    }
  } else if (children) {
    // compiled element vnode - if children is passed, only possible types are
    // string or Array.
    vnode.shapeFlag |= isString(children)
      ? ShapeFlags.TEXT_CHILDREN
      : ShapeFlags.ARRAY_CHILDREN
  }

  // validate key
  if (__DEV__ && vnode.key !== vnode.key) {
    warn(`VNode created with invalid key (NaN). VNode type:`, vnode.type)
  }

  // track vnode for block tree
  if (
    isBlockTreeEnabled > 0 &&
    // avoid a block node from tracking itself
    !isBlockNode &&
    // has current parent block
    currentBlock &&
    // presence of a patch flag indicates this node needs patching on updates.
    // component nodes also should always be patched, because even if the
    // component doesn't need to update, it needs to persist the instance on to
    // the next vnode so that it can be properly unmounted later.
    (vnode.patchFlag > 0 || shapeFlag & ShapeFlags.COMPONENT) &&
    // the EVENTS flag is only for hydration and if it is the only flag, the
    // vnode should not be considered dynamic due to handler caching.
    vnode.patchFlag !== PatchFlags.HYDRATE_EVENTS
  ) {
    currentBlock.push(vnode)
  }

  if (__COMPAT__) {
    convertLegacyVModelProps(vnode)
    defineLegacyVNodeProperties(vnode)
  }

  return vnode
}

五、mount里的render方法

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的render

const render: RootRenderFunction = (vnode, container, isSVG) => {
    if (vnode == null) { // 虚拟节点不存在，则销毁
      if (container._vnode) {
        unmount(container._vnode, null, null, true)
      }
    } else { // 虚拟节点存在，则更新或创建
      patch(container._vnode || null, vnode, container, null, null, null, isSVG)
    }
    flushPreFlushCbs()
    flushPostFlushCbs()
    container._vnode = vnode // 缓存虚拟节点数据，作为已完成渲染的标识
  }

1、patch(container._vnode || null, vnode, container, null, null, null, isSVG)

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的patch patch 方法核心目标就是 比较 新老 vnode 节点 并对其进行差异的操作. 在初始化渲染时 , 会先 patch 我们的根组件 . 于是会走到 processComponent 这个逻辑分支

 const patch: PatchFn = (
    n1,
    n2,
    container,
    anchor = null,
    parentComponent = null,
    parentSuspense = null,
    isSVG = false,
    slotScopeIds = null,
    optimized = __DEV__ && isHmrUpdating ? false : !!n2.dynamicChildren
  ) => {
    // 节点相同就返回
    if (n1 === n2) {
      return
    }

    // patching & not same type, unmount old tree
    if (n1 && !isSameVNodeType(n1, n2)) {
      anchor = getNextHostNode(n1)
      unmount(n1, parentComponent, parentSuspense, true)
      n1 = null
    }

    if (n2.patchFlag === PatchFlags.BAIL) {
      optimized = false
      n2.dynamicChildren = null
    }

    const { type, ref, shapeFlag } = n2
    switch (type) {
      case Text:
        processText(n1, n2, container, anchor)
        break
      case Comment:
        processCommentNode(n1, n2, container, anchor)
        break
      case Static:
        if (n1 == null) {
          mountStaticNode(n2, container, anchor, isSVG)
        } else if (__DEV__) {
          patchStaticNode(n1, n2, container, isSVG)
        }
        break
      case Fragment:
        processFragment(
          n1,
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        break
      default:
        if (shapeFlag & ShapeFlags.ELEMENT) {
          processElement(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & ShapeFlags.COMPONENT) {
          processComponent(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & ShapeFlags.TELEPORT) {
          ;(type as typeof TeleportImpl).process(
            n1 as TeleportVNode,
            n2 as TeleportVNode,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else if (__FEATURE_SUSPENSE__ && shapeFlag & ShapeFlags.SUSPENSE) {
          ;(type as typeof SuspenseImpl).process(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else if (__DEV__) {
          warn('Invalid VNode type:', type, `(${typeof type})`)
        }
    }

    // set ref
    if (ref != null && parentComponent) {
      setRef(ref, n1 && n1.ref, parentSuspense, n2 || n1, !n2)
    }
  }

以上会执行到

2、processComponent

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的processComponent

  const processComponent = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    n2.slotScopeIds = slotScopeIds
    if (n1 == null) {
      if (n2.shapeFlag & ShapeFlags.COMPONENT_KEPT_ALIVE) {
        // 如果 新vnode 是 KEPT_ALIVE
        ;(parentComponent!.ctx as KeepAliveContext).activate(
          n2,
          container,
          anchor,
          isSVG,
          optimized
        )
      } else {
        // 挂载节点
        mountComponent(
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          optimized
        )
      }
    } else {
      // 对比更新
      updateComponent(n1, n2, optimized)
    }
  }

会执行到挂载节点mountComponent

3、mountComponent

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的mountComponent

const mountComponent: MountComponentFn = (
    initialVNode,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    // 2.x compat may pre-create the component instance before actually
    // mounting
    const compatMountInstance =
      __COMPAT__ && initialVNode.isCompatRoot && initialVNode.component
    const instance: ComponentInternalInstance =
      compatMountInstance ||
      (initialVNode.component = createComponentInstance(
        initialVNode,
        parentComponent,
        parentSuspense
      ))

    if (__DEV__ && instance.type.__hmrId) {
      registerHMR(instance)
    }

    if (__DEV__) {
      pushWarningContext(initialVNode)
      startMeasure(instance, `mount`)
    }

    // inject renderer internals for keepAlive
    if (isKeepAlive(initialVNode)) {
      ;(instance.ctx as KeepAliveContext).renderer = internals
    }

    // resolve props and slots for setup context
    if (!(__COMPAT__ && compatMountInstance)) {
      if (__DEV__) {
        // 性能分析
        startMeasure(instance, `init`)
      }
      setupComponent(instance)
      if (__DEV__) {
        endMeasure(instance, `init`)
      }
    }

    // setup() is async. This component relies on async logic to be resolved
    // before proceeding
    if (__FEATURE_SUSPENSE__ && instance.asyncDep) {
      parentSuspense && parentSuspense.registerDep(instance, setupRenderEffect)

      // Give it a placeholder if this is not hydration
      // TODO handle self-defined fallback
      if (!initialVNode.el) {
        const placeholder = (instance.subTree = createVNode(Comment))
        processCommentNode(null, placeholder, container!, anchor)
      }
      return
    }

4、setupComponent(instance)

export function setupComponent(
  instance: ComponentInternalInstance,
  isSSR = false
) {
  isInSSRComponentSetup = isSSR

  const { props, children } = instance.vnode
  const isStateful = isStatefulComponent(instance)
  initProps(instance, props, isStateful, isSSR)
  initSlots(instance, children)

  const setupResult = isStateful
    ? setupStatefulComponent(instance, isSSR)
    : undefined
  isInSSRComponentSetup = false
  return setupResult
}

这个方法中初始化了插槽 和 props , 结束之后会先判断这个 component 是否是 stateful 的(根据 component 的 shapeFlag)

我们重点看后面, 他试图获取 setup 的执行结果, 从而通过调用 setupStatefulComponent 方法开始解析 setup

5、setupStatefulComponent

function setupStatefulComponent(
  instance: ComponentInternalInstance,
  isSSR: boolean
) {
  // 此时 instance.type === 用户注册的 setup + 容器下面的 innerHTML
  const Component = instance.type as ComponentOptions

  if (__DEV__) {
    if (Component.name) {
      validateComponentName(Component.name, instance.appContext.config)
    }
    if (Component.components) {
      const names = Object.keys(Component.components)
      for (let i = 0; i < names.length; i++) {
        validateComponentName(names[i], instance.appContext.config)
      }
    }
    if (Component.directives) {
      const names = Object.keys(Component.directives)
      for (let i = 0; i < names.length; i++) {
        validateDirectiveName(names[i])
      }
    }
    if (Component.compilerOptions && isRuntimeOnly()) {
      warn(
        `"compilerOptions" is only supported when using a build of Vue that ` +
          `includes the runtime compiler. Since you are using a runtime-only ` +
          `build, the options should be passed via your build tool config instead.`
      )
    }
  }
  // 0. create render proxy property access cache
  instance.accessCache = Object.create(null)
  // 1. create public instance / render proxy
  // also mark it raw so it's never observed
  instance.proxy = markRaw(new Proxy(instance.ctx, PublicInstanceProxyHandlers))
  if (__DEV__) {
    exposePropsOnRenderContext(instance)
  }
  // 2. call setup()
  const { setup } = Component
  if (setup) {
    const setupContext = (instance.setupContext =
      setup.length > 1 ? createSetupContext(instance) : null)

    setCurrentInstance(instance)
    pauseTracking()
    const setupResult = callWithErrorHandling(
      setup,
      instance,
      ErrorCodes.SETUP_FUNCTION,
      [__DEV__ ? shallowReadonly(instance.props) : instance.props, setupContext]
    )
    resetTracking()
    unsetCurrentInstance()

    if (isPromise(setupResult)) {
      setupResult.then(unsetCurrentInstance, unsetCurrentInstance)
      if (isSSR) {
        // return the promise so server-renderer can wait on it
        return setupResult
          .then((resolvedResult: unknown) => {
            handleSetupResult(instance, resolvedResult, isSSR)
          })
          .catch(e => {
            handleError(e, instance, ErrorCodes.SETUP_FUNCTION)
          })
      } else if (__FEATURE_SUSPENSE__) {
        // async setup returned Promise.
        // bail here and wait for re-entry.
        instance.asyncDep = setupResult
        if (__DEV__ && !instance.suspense) {
          const name = Component.name ?? 'Anonymous'
          warn(
            `Component <${name}>: setup function returned a promise, but no ` +
              `<Suspense> boundary was found in the parent component tree. ` +
              `A component with async setup() must be nested in a <Suspense> ` +
              `in order to be rendered.`
          )
        }
      } else if (__DEV__) {
        warn(
          `setup() returned a Promise, but the version of Vue you are using ` +
            `does not support it yet.`
        )
      }
    } else {
      handleSetupResult(instance, setupResult, isSSR)
    }
  } else {
    finishComponentSetup(instance, isSSR)
  }
}

以下是instance.type的截图，是用户注册的 setup + 容器下面的 innerHTML

• callWithErrorHandling 即将执行callWithErrorHandling

传参setup是个函数

运行中的callWithErrorHandling

callWithErrorHandling运行的结果

• handleSetupResult(instance, setupResult, isSSR)

export function handleSetupResult(
  instance: ComponentInternalInstance,
  setupResult: unknown,
  isSSR: boolean
) {
  if (isFunction(setupResult)) {
    // setup returned an inline render function
    // setup 中 返回用户自定义 render function
    if (__SSR__ && (instance.type as ComponentOptions).__ssrInlineRender) {
      // when the function's name is `ssrRender` (compiled by SFC inline mode),
      // set it as ssrRender instead.
      // 如果当前运行时是 node
      instance.ssrRender = setupResult
    } else {
    // 在实例上挂载 renderFunction
      instance.render = setupResult as InternalRenderFunction
    }
  } else if (isObject(setupResult)) {
    if (__DEV__ && isVNode(setupResult)) {
      warn(
        `setup() should not return VNodes directly - ` +
          `return a render function instead.`
      )
    }
    // setup returned bindings.
    // assuming a render function compiled from template is present.
    if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
      instance.devtoolsRawSetupState = setupResult
    }
    // 把结果添加到 实例的 setupState 中
    instance.setupState = proxyRefs(setupResult)
    if (__DEV__) {
      exposeSetupStateOnRenderContext(instance)
    }
  } else if (__DEV__ && setupResult !== undefined) {
    warn(
      `setup() should return an object. Received: ${
        setupResult === null ? 'null' : typeof setupResult
      }`
    )
  }
  finishComponentSetup(instance, isSSR)
}

proxyRefs源码

• finishComponentSetup

获取 render function && 兼容 vue2.x 做的事情：

• 生成渲染函数：Component.render = compile(template, finalCompilerOptions)

• 支持vue2.x:

  // support for 2.x options
  if (__FEATURE_OPTIONS_API__ && !(__COMPAT__ && skipOptions)) {
    setCurrentInstance(instance)
    pauseTracking()
    applyOptions(instance)
    resetTracking()
    unsetCurrentInstance()
  }

export function finishComponentSetup(
  instance: ComponentInternalInstance,
  isSSR: boolean,
  skipOptions?: boolean
) {
  const Component = instance.type as ComponentOptions

  if (__COMPAT__) {
    convertLegacyRenderFn(instance)

    if (__DEV__ && Component.compatConfig) {
      validateCompatConfig(Component.compatConfig)
    }
  }

  // template / render function normalization
  // could be already set when returned from setup()
  if (!instance.render) {
    // only do on-the-fly compile if not in SSR - SSR on-the-fly compilation
    // is done by server-renderer
    if (!isSSR && compile && !Component.render) {
      const template =
        (__COMPAT__ &&
          instance.vnode.props &&
          instance.vnode.props['inline-template']) ||
        Component.template ||
        resolveMergedOptions(instance).template
      if (template) {
        if (__DEV__) {
          startMeasure(instance, `compile`)
        }
        const { isCustomElement, compilerOptions } = instance.appContext.config
        const { delimiters, compilerOptions: componentCompilerOptions } =
          Component
        const finalCompilerOptions: CompilerOptions = extend(
          extend(
            {
              isCustomElement,
              delimiters
            },
            compilerOptions
          ),
          componentCompilerOptions
        )
        if (__COMPAT__) {
          // pass runtime compat config into the compiler
          finalCompilerOptions.compatConfig = Object.create(globalCompatConfig)
          if (Component.compatConfig) {
            // @ts-expect-error types are not compatible
            extend(finalCompilerOptions.compatConfig, Component.compatConfig)
          }
        }
        Component.render = compile(template, finalCompilerOptions)
        if (__DEV__) {
          endMeasure(instance, `compile`)
        }
      }
    }

    instance.render = (Component.render || NOOP) as InternalRenderFunction

    // for runtime-compiled render functions using `with` blocks, the render
    // proxy used needs a different `has` handler which is more performant and
    // also only allows a whitelist of globals to fallthrough.
    if (installWithProxy) {
      installWithProxy(instance)
    }
  }

  // support for 2.x options
  if (__FEATURE_OPTIONS_API__ && !(__COMPAT__ && skipOptions)) {
    setCurrentInstance(instance)
    pauseTracking()
    applyOptions(instance)
    resetTracking()
    unsetCurrentInstance()
  }

  // warn missing template/render
  // the runtime compilation of template in SSR is done by server-render
  if (__DEV__ && !Component.render && instance.render === NOOP && !isSSR) {
    /* istanbul ignore if */
    if (!compile && Component.template) {
      warn(
        `Component provided template option but ` +
          `runtime compilation is not supported in this build of Vue.` +
          (__ESM_BUNDLER__
            ? ` Configure your bundler to alias "vue" to "vue/dist/vue.esm-bundler.js".`
            : __ESM_BROWSER__
            ? ` Use "vue.esm-browser.js" instead.`
            : __GLOBAL__
            ? ` Use "vue.global.js" instead.`
            : ``) /* should not happen */
      )
    } else {
      warn(`Component is missing template or render function.`)
    }
  }
}

六、执行mountComponent中的setupRenderEffect方法

主要功能：依赖收集 , 初始化渲染 , 后续的更新 源码位置源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的setupRenderEffect

  const setupRenderEffect: SetupRenderEffectFn = (
    instance,
    initialVNode,
    container,
    anchor,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    const componentUpdateFn = () => {
      if (!instance.isMounted) {
        let vnodeHook: VNodeHook | null | undefined
        const { el, props } = initialVNode
        const { bm, m, parent } = instance
        const isAsyncWrapperVNode = isAsyncWrapper(initialVNode)

        toggleRecurse(instance, false)
        // beforeMount hook
        if (bm) {
          invokeArrayFns(bm)
        }
        // onVnodeBeforeMount
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeBeforeMount)
        ) {
          invokeVNodeHook(vnodeHook, parent, initialVNode)
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          instance.emit('hook:beforeMount')
        }
        toggleRecurse(instance, true)

        if (el && hydrateNode) {
          // vnode has adopted host node - perform hydration instead of mount.
          const hydrateSubTree = () => {
            if (__DEV__) {
              startMeasure(instance, `render`)
            }
            instance.subTree = renderComponentRoot(instance)
            if (__DEV__) {
              endMeasure(instance, `render`)
            }
            if (__DEV__) {
              startMeasure(instance, `hydrate`)
            }
            hydrateNode!(
              el as Node,
              instance.subTree,
              instance,
              parentSuspense,
              null
            )
            if (__DEV__) {
              endMeasure(instance, `hydrate`)
            }
          }

          if (isAsyncWrapperVNode) {
            ;(initialVNode.type as ComponentOptions).__asyncLoader!().then(
              // note: we are moving the render call into an async callback,
              // which means it won't track dependencies - but it's ok because
              // a server-rendered async wrapper is already in resolved state
              // and it will never need to change.
              () => !instance.isUnmounted && hydrateSubTree()
            )
          } else {
            hydrateSubTree()
          }
        } else {
          if (__DEV__) {
            startMeasure(instance, `render`)
          }
          const subTree = (instance.subTree = renderComponentRoot(instance))
          if (__DEV__) {
            endMeasure(instance, `render`)
          }
          if (__DEV__) {
            startMeasure(instance, `patch`)
          }
          patch(
            null,
            subTree,
            container,
            anchor,
            instance,
            parentSuspense,
            isSVG
          )
          if (__DEV__) {
            endMeasure(instance, `patch`)
          }
          initialVNode.el = subTree.el
        }
        // mounted hook
        if (m) {
          queuePostRenderEffect(m, parentSuspense)
        }
        // onVnodeMounted
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeMounted)
        ) {
          const scopedInitialVNode = initialVNode
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook!, parent, scopedInitialVNode),
            parentSuspense
          )
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          queuePostRenderEffect(
            () => instance.emit('hook:mounted'),
            parentSuspense
          )
        }

        // activated hook for keep-alive roots.
        // #1742 activated hook must be accessed after first render
        // since the hook may be injected by a child keep-alive
        if (
          initialVNode.shapeFlag & ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE ||
          (parent &&
            isAsyncWrapper(parent.vnode) &&
            parent.vnode.shapeFlag & ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE)
        ) {
          instance.a && queuePostRenderEffect(instance.a, parentSuspense)
          if (
            __COMPAT__ &&
            isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
          ) {
            queuePostRenderEffect(
              () => instance.emit('hook:activated'),
              parentSuspense
            )
          }
        }
        instance.isMounted = true

        if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
          devtoolsComponentAdded(instance)
        }

        // #2458: deference mount-only object parameters to prevent memleaks
        initialVNode = container = anchor = null as any
      } else {
        // updateComponent
        // This is triggered by mutation of component's own state (next: null)
        // OR parent calling processComponent (next: VNode)
        let { next, bu, u, parent, vnode } = instance
        let originNext = next
        let vnodeHook: VNodeHook | null | undefined
        if (__DEV__) {
          pushWarningContext(next || instance.vnode)
        }

        // Disallow component effect recursion during pre-lifecycle hooks.
        toggleRecurse(instance, false)
        if (next) {
          next.el = vnode.el
          updateComponentPreRender(instance, next, optimized)
        } else {
          next = vnode
        }

        // beforeUpdate hook
        if (bu) {
          invokeArrayFns(bu)
        }
        // onVnodeBeforeUpdate
        if ((vnodeHook = next.props && next.props.onVnodeBeforeUpdate)) {
          invokeVNodeHook(vnodeHook, parent, next, vnode)
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          instance.emit('hook:beforeUpdate')
        }
        toggleRecurse(instance, true)

        // render
        if (__DEV__) {
          startMeasure(instance, `render`)
        }
        const nextTree = renderComponentRoot(instance)
        if (__DEV__) {
          endMeasure(instance, `render`)
        }
        const prevTree = instance.subTree
        instance.subTree = nextTree

        if (__DEV__) {
          startMeasure(instance, `patch`)
        }
        patch(
          prevTree,
          nextTree,
          // parent may have changed if it's in a teleport
          hostParentNode(prevTree.el!)!,
          // anchor may have changed if it's in a fragment
          getNextHostNode(prevTree),
          instance,
          parentSuspense,
          isSVG
        )
        if (__DEV__) {
          endMeasure(instance, `patch`)
        }
        next.el = nextTree.el
        if (originNext === null) {
          // self-triggered update. In case of HOC, update parent component
          // vnode el. HOC is indicated by parent instance's subTree pointing
          // to child component's vnode
          updateHOCHostEl(instance, nextTree.el)
        }
        // updated hook
        if (u) {
          queuePostRenderEffect(u, parentSuspense)
        }
        // onVnodeUpdated
        if ((vnodeHook = next.props && next.props.onVnodeUpdated)) {
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook!, parent, next!, vnode),
            parentSuspense
          )
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          queuePostRenderEffect(
            () => instance.emit('hook:updated'),
            parentSuspense
          )
        }

        if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
          devtoolsComponentUpdated(instance)
        }

        if (__DEV__) {
          popWarningContext()
        }
      }
    }

    // create reactive effect for rendering
    const effect = (instance.effect = new ReactiveEffect(
      componentUpdateFn,
      () => queueJob(update),
      instance.scope // track it in component's effect scope
    ))

    const update: SchedulerJob = (instance.update = () => effect.run())
    update.id = instance.uid
    // allowRecurse
    // #1801, #2043 component render effects should allow recursive updates
    toggleRecurse(instance, true)

    if (__DEV__) {
      effect.onTrack = instance.rtc
        ? e => invokeArrayFns(instance.rtc!, e)
        : void 0
      effect.onTrigger = instance.rtg
        ? e => invokeArrayFns(instance.rtg!, e)
        : void 0
      update.ownerInstance = instance
    }

    update()
  }

• 生成subTree

可以看到这个方法把我们容器下的所有节点变成了 vnode .验证完 vnode 的合法性之后, 会合并和继承一些属性. 最终把 vnode 返回.

renderComponentRoot()源码路径：packages/runtime-core/src/componentRenderUtils.ts

export function renderComponentRoot(
  instance: ComponentInternalInstance
): VNode {
  const {
    type: Component,
    vnode,
    proxy,
    withProxy,
    props,
    propsOptions: [propsOptions],
    slots,
    attrs,
    emit,
    render,
    renderCache,
    data,
    setupState,
    ctx,
    inheritAttrs
  } = instance

  let result
  let fallthroughAttrs
  const prev = setCurrentRenderingInstance(instance)
  if (__DEV__) {
    accessedAttrs = false
  }

  try {
    if (vnode.shapeFlag & ShapeFlags.STATEFUL_COMPONENT) {
      // withProxy is a proxy with a different `has` trap only for
      // runtime-compiled render functions using `with` block.

      // 这里调用了 先调用 render
      // 调用之后我们会拿到 容器下 节点的 vnode tree
      // 之后校验 vnode tree 是否是合法的 vnode
      // 如果拿到的是合法的 vnode 就赋值给 result
      // 在这里进行的依赖收集
      const proxyToUse = withProxy || proxy
      result = normalizeVNode(
        render!.call(
          proxyToUse,
          proxyToUse!,
          renderCache,
          props,
          setupState,
          data,
          ctx
        )
      )
      fallthroughAttrs = attrs
    } else {
      // functional
      const render = Component as FunctionalComponent
      // in dev, mark attrs accessed if optional props (attrs === props)
      if (__DEV__ && attrs === props) {
        markAttrsAccessed()
      }
      result = normalizeVNode(
        render.length > 1
          ? render(
              props,
              __DEV__
                ? {
                    get attrs() {
                      markAttrsAccessed()
                      return attrs
                    },
                    slots,
                    emit
                  }
                : { attrs, slots, emit }
            )
          : render(props, null as any /* we know it doesn't need it */)
      )
      fallthroughAttrs = Component.props
        ? attrs
        : getFunctionalFallthrough(attrs)
    }
  } catch (err) {
    blockStack.length = 0
    handleError(err, instance, ErrorCodes.RENDER_FUNCTION)
    result = createVNode(Comment)
  }

  // attr merging
  // in dev mode, comments are preserved, and it's possible for a template
  // to have comments along side the root element which makes it a fragment
  let root = result
  let setRoot: SetRootFn = undefined
  if (
    __DEV__ &&
    result.patchFlag > 0 &&
    result.patchFlag & PatchFlags.DEV_ROOT_FRAGMENT
  ) {
    ;[root, setRoot] = getChildRoot(result)
  }

  if (fallthroughAttrs && inheritAttrs !== false) {
    const keys = Object.keys(fallthroughAttrs)
    const { shapeFlag } = root
    if (keys.length) {
      if (shapeFlag & (ShapeFlags.ELEMENT | ShapeFlags.COMPONENT)) {
        if (propsOptions && keys.some(isModelListener)) {
          // If a v-model listener (onUpdate:xxx) has a corresponding declared
          // prop, it indicates this component expects to handle v-model and
          // it should not fallthrough.
          // related: #1543, #1643, #1989
          fallthroughAttrs = filterModelListeners(
            fallthroughAttrs,
            propsOptions
          )
        }
        root = cloneVNode(root, fallthroughAttrs)
      } else if (__DEV__ && !accessedAttrs && root.type !== Comment) {
        const allAttrs = Object.keys(attrs)
        const eventAttrs: string[] = []
        const extraAttrs: string[] = []
        for (let i = 0, l = allAttrs.length; i < l; i++) {
          const key = allAttrs[i]
          if (isOn(key)) {
            // ignore v-model handlers when they fail to fallthrough
            if (!isModelListener(key)) {
              // remove `on`, lowercase first letter to reflect event casing
              // accurately
              eventAttrs.push(key[2].toLowerCase() + key.slice(3))
            }
          } else {
            extraAttrs.push(key)
          }
        }
        if (extraAttrs.length) {
          warn(
            `Extraneous non-props attributes (` +
              `${extraAttrs.join(', ')}) ` +
              `were passed to component but could not be automatically inherited ` +
              `because component renders fragment or text root nodes.`
          )
        }
        if (eventAttrs.length) {
          warn(
            `Extraneous non-emits event listeners (` +
              `${eventAttrs.join(', ')}) ` +
              `were passed to component but could not be automatically inherited ` +
              `because component renders fragment or text root nodes. ` +
              `If the listener is intended to be a component custom event listener only, ` +
              `declare it using the "emits" option.`
          )
        }
      }
    }
  }

  if (
    __COMPAT__ &&
    isCompatEnabled(DeprecationTypes.INSTANCE_ATTRS_CLASS_STYLE, instance) &&
    vnode.shapeFlag & ShapeFlags.STATEFUL_COMPONENT &&
    root.shapeFlag & (ShapeFlags.ELEMENT | ShapeFlags.COMPONENT)
  ) {
    const { class: cls, style } = vnode.props || {}
    if (cls || style) {
      if (__DEV__ && inheritAttrs === false) {
        warnDeprecation(
          DeprecationTypes.INSTANCE_ATTRS_CLASS_STYLE,
          instance,
          getComponentName(instance.type)
        )
      }
      root = cloneVNode(root, {
        class: cls,
        style: style
      })
    }
  }

  // inherit directives
  if (vnode.dirs) {
    if (__DEV__ && !isElementRoot(root)) {
      warn(
        `Runtime directive used on component with non-element root node. ` +
          `The directives will not function as intended.`
      )
    }
    // clone before mutating since the root may be a hoisted vnode
    root = cloneVNode(root)
    root.dirs = root.dirs ? root.dirs.concat(vnode.dirs) : vnode.dirs
  }
  // inherit transition data
  if (vnode.transition) {
    if (__DEV__ && !isElementRoot(root)) {
      warn(
        `Component inside <Transition> renders non-element root node ` +
          `that cannot be animated.`
      )
    }
    root.transition = vnode.transition
  }

  if (__DEV__ && setRoot) {
    setRoot(root)
  } else {
    result = root
  }

  setCurrentRenderingInstance(prev)
  return result
}

• 接着执行patch

// 会执行到这个逻辑
if (shapeFlag & ShapeFlags.ELEMENT) {
  // 此时我们会进入这个条件
  processElement(
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  )
}

七、processElement

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的processElement

  const processElement = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    isSVG = isSVG || (n2.type as string) === 'svg'
    if (n1 == null) { // 老节点不存在，挂载
      mountElement(
        n2,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    } else {
      patchElement( // 存在 对比更新
        n1,
        n2,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }

八、mountElement

源码位置在packages/runtime-core/src/renderer.ts的 baseCreateRenderer里面的mountElement

  const mountElement = (
    vnode: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    let el: RendererElement
    let vnodeHook: VNodeHook | undefined | null
    const { type, props, shapeFlag, transition, patchFlag, dirs } = vnode
    // 走这里 !
    // 调用 hostCreateElement 创建真实 DOM
    el = vnode.el = hostCreateElement(
      vnode.type as string,
      isSVG,
      props && props.is,
      props
    )
    // 子节点如果是 文本
    if (shapeFlag & ShapeFlags.TEXT_CHILDREN) {
      // 操作 dom 赋值 text
      hostSetElementText(el, vnode.children as string)
    }
    // 子节点如果是 数组
    else if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
      // 挂载子节点
      mountChildren(
        vnode.children as VNodeArrayChildren,
        el, // 父节点
        null,
        parentComponent,
        parentSuspense,
        isSVG && type !== 'foreignObject',
        slotScopeIds,
        optimized || !!vnode.dynamicChildren
      )
    }

    // 如果当前元素有 props
    if (props) {
      // 遍历 props
      for (const key in props) {
        if (!isReservedProp(key)) {
          // 给元素打 属性补丁
          hostPatchProp(
            el,
            key,
            null,
            props[key],
            isSVG,
            vnode.children as VNode[],
            parentComponent,
            parentSuspense,
            unmountChildren
          )
        }
      }
    }
    // 将当前操作节点 插入到对应容器下
    hostInsert(el, container, anchor)
  }

• 创建真实Dom

el = vnode.el = hostCreateElement(
      vnode.type as string,
      isSVG,
      props && props.is,
      props
    )

• 递归遍历挂载子元素

• 子节点挂载完成之后

• hostInsert挂载到父元素

九、总结

整个渲染流程：创建渲染器 --> 创建 app 实例 --> 调用 mount 方法 --> 创建 vnode (基于初始化时传入的 option) --> 调用 render --> patch --> processComponent --> mountComponent --> 调用 setup 获取他的结果 -> 调用 compile 获取容器下 innerHTML 的 render function -> 兼容 vue2.x 的 API --> setupRenderEffect --> 构建 subTree --> processElement --> mountElement --> 递归 patch 子元素 --> 添加 props --> 插入到对应父节点下。

参考

vue3初始化渲染流程

Vue3响应式源码分析 - ref + ReactiveEffect篇