Initializing vuE3 source code parsing

Vue3 source code analysis

Depend on the installation

yarn --ignore-scripts
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Ready to debug

Add – sourcemap

"dev": "node scripts/dev.js --sourcemap",
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Perform yarn dev

Entrance to the file

Start by running the NPM run dev command

// "dev": "node scripts/dev.js --sourcemap"
// find scripts/dev.js find TARGET is vue by default
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Start with the rollup package configuration file rollup.config.js

// Package the entry file
SRC /index.ts SRC /index.ts
// Runtime WebPack runtime version
const entryFile = /runtime$/.test(format) ? `src/runtime.ts` : `src/index.ts`

// packages/
const packagesDir = path.resolve(__dirname, 'packages')
// Default packages/vue
const packageDir = path.resolve(packagesDir, process.env.TARGET)
const name = path.basename(packageDir)
const resolve = p= > path.resolve(packageDir, p)

// Import file configuration
// input: resolve(entryFile),
/ / find entry files are packages/vue/SRC/index. The ts
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The SRC /index.ts file finally exports all the methods in the Runtime-dom including createApp
```
export * from '@vue/runtime-dom'
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```

CreateApp method

// runtime-dom.ts
export const createApp = ((. args) = > {
   // Get a renderer first
   The createApp method is actually provided by the renderer
   constapp = ensureRenderer().createApp(... args)/ /... Some code is omitted here
   return app
}
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The ensureRenderer method is called in createApp

import {
  createRenderer,
} from '@vue/runtime-core'
function ensureRenderer() {
  / / the renderer
  // Singleton mode
  // Return if it exists, create if it does not exist
  return renderer || (renderer = createRenderer<Node, Element>(rendererOptions))
}
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CreateRenderer is called again in the ensureRenderer method

Open @ vue/runtime – core/index. The ts

CreateRenderer from. / the renderer. Ts

// @vue/runtime-core/index.ts
export { createRenderer } from './renderer'
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// ./renderer.ts
export function createRenderer<
  HostNode = RendererNode.HostElement = RendererElement> (options: RendererOptions<HostNode, HostElement>) {
  return baseCreateRenderer<HostNode, HostElement>(options)
}
/* export function createRenderer(options) { return baseCreateRenderer(options) } */
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The baseCreateRenderer function is almost 2000 lines of code (the renderer’s factory function)
Finally, I gave up and decided to start with the return value at the bottom

So I’m going to skip the rest of the code

function baseCreateRenderer(options: RendererOptions, createHydrationFns? :typeof createHydrationFunctions
) :any {

  / /... I'm going to omit 2000 lines of code
      
  // The object returned here is the renderer
  // There are three methods
  return {
    Render (vnode, container); render(vnode, container);
    render,
    // Water injection for server rendering
    hydrate,
    // The method to create an application instance
    createApp: createAppAPI(render, hydrate)
  }
}
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CreateApp is returned by the createAppAPI method

The following methods all revert back to the app instance, so they can be called chained

Compared to Vue2, the following methods are converted from static methods to instance methods

// Why adjust to instance methods?
  // 1. Avoid contamination between instances
  // 2
  // 3. Tree-shake
     // Tree shaking:
          Use ({install(){}}) initializes a plug-in
          // But in the code, this plug-in is not actually used
          // The plugin will not be packaged when the code is packaged
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I’m so happy to finally see so many old friends

// import { createAppAPI, CreateAppFunction } from './apiCreateApp'
// packages\runtime-core\src\apiCreateApp.ts
export function createAppAPI<HostElement> (render: RootRenderFunction, hydrate? : RootHydrateFunction) :CreateAppFunction<HostElement> {
  // The method returned from the outside
  return function createApp(rootComponent, rootProps = null) {
    if(rootProps ! =null && !isObject(rootProps)) {
      rootProps = null
    }

    const context = createAppContext()
    const installedPlugins = new Set(a)let isMounted = false

    // Application instance
    const app: App = (context.app = {
      _uid: uid++,
      _component: rootComponent as ConcreteComponent,
      _props: rootProps,
      _container: null._context: context,

      version,

      get config() {
        return context.config
      },

      set config(v) {/ *... * /},
      // The plugin uses the method initialization
      // The first argument passed in is the app instance
      // The first argument passed in vue2 is Vue itself (constructor)
      use(plugin: Plugin, ... options: any[]) {
   		if(plugin && isFunction(plugin.install)) { installedPlugins.add(plugin) plugin.install(app, ... options) }else if(isFunction(plugin)) { installedPlugins.add(plugin) plugin(app, ... options) }return app
      },
      // Blend method initialization
      mixin(mixin: ComponentOptions) {
        if (__FEATURE_OPTIONS_API__) {
          if(! context.mixins.includes(mixin)) { context.mixins.push(mixin)// global mixin with props/emits de-optimizes props/emits
            // normalization caching.
            if (mixin.props || mixin.emits) {
              context.deopt = true}}}return app
      },
      // Initialize the component methodcomponent(name: string, component? : Component): any {if(! component) {return context.components[name]
        }
        context.components[name] = component
        return app
      },
	 // Initialize the instruction method
      directive(name: string, directive? : Directive) {
        if(! directive) {return context.directives[name] as any
        }
        context.directives[name] = directive
        return app
      },
      // Mount initialization goes heremount( rootContainer: HostElement, isHydrate? : boolean, isSVG? : boolean ): any {if(! isMounted) {// Initializes the virtual DOM tree
          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
            
          if (isHydrate && hydrate) {
            hydrate(vnode as VNode<Node, Element>, rootContainer as any)
          } else {
            // This is not the server rendering, the client rendering goes here by default
            render(vnode, rootContainer, isSVG)
          }
          isMounted = true
          app._container = rootContainer
          // for devtools and telemetry; (rootContaineras any).__vue_app__ = app

          returnvnode.component! .proxy } },// Uninstall initialization
      unmount() {
        if (isMounted) {
          render(null, app._container)
          delete app._container.__vue_app__
        }
      },
      Dependency injection multi-level nested communication
      provide(key, value) {
        // TypeScript doesn't allow symbols as index type
        // https://github.com/Microsoft/TypeScript/issues/24587
        context.provides[key as string] = value
        return app
      }
    })
    return app
  }
}
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To mount the disk, mount the disk

The render function is finally executed inside mount

// Mount internal implementation
// This is not the server rendering, the client rendering goes here by default
render(vnode, rootContainer, isSVG)
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Patch is executed in the render function

// Initialization goes here, which is similar to vue2
// Update if parameter 1 exists
// If parameter 1 does not exist, go to the mount process
const render: RootRenderFunction = (vnode, container, isSVG) = > {
    / /... Omit some code
    patch(container._vnode || null, vnode, container, null.null.null, isSVG)
    / /... Omit some code
}

// Pacth internally distinguishes text comment static nodes (nodes that do not change)
// Fragment Abstract virtual node (parent container). Vue2 can have only one node. Vue3 can have multiple nodes
// Element node components, etc

case Text:
        processText(n1, n2, container, anchor)
case Comment:
        processCommentNode(n1, n2, container, anchor)
/ /... Omit some code
default:
	/ /... Omit some code
	else if (shapeFlag & ShapeFlags.COMPONENT) {
        // Initialization goes here
        // Because the following is done when initializing the mount
        Const vNode = createVNode(rootComponent as ConcreteComponent,) const vNode = createVNode(rootComponent as ConcreteComponent,); // Render (vnode, rootContainer, isSVG) */
        processComponent(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
        )
    }
	/ /... Omit some code
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Then initialize the line processComponent

The mountComponent method is executed because n1(the old vNode) does not exist
In vue2 mountComponent declares the updateComponent function new and a render Watcher does the dependency collection for component granularity
- And Vnode patch operation vm._update(vm._render(), hydrating), which generates the real node and finally performs the root node replacement operation, nodeops.insertbefore to the page
- And callHook(VM, ‘beforeMount ‘) and callHook(VM, ‘mounted’)
This is obviously what Vue3 does, converting vNodes into real DOM and updating setupComponent installation

const processComponent = (
    n1: VNode | null./ / the old vnode
    n2: VNode,  / / new vnode
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) = > {
    n2.slotScopeIds = slotScopeIds
    // Initialize container to null because container is the id passed in when #app calls mount
    // There are no old vNodes
    if (n1 == null) {
       // Whether to cache components for keep-alive
       // when initialized n2 is a vNode non-cached component converted from createApp options
      if(n2.shapeFlag & ShapeFlags.COMPONENT_KEPT_ALIVE) { ; (parentComponent! .ctxas KeepAliveContext).activate(
          n2,
          container,
          anchor,
          isSVG,
          optimized
        )
      } else {
        // So the initialization goes here, i.e. the initial mount is handled here
        mountComponent(
          n2, / / new vnode
          container, // #app
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          optimized
        )
      }
    } else {
      // Verify that the old vNode is updated and the mountComponent is not mounted
      updateComponent(n1, n2, optimized)
    }
  }
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Then initialize the mountComponent above

Creating a component instance
Added render function side effects

const mountComponent: MountComponentFn = (initialVNode, container, anchor, parentComponent, parentSuspense, isSVG, optimized) = > {
  // 1. Create a component instance
  const instance: ComponentInternalInstance = (initialVNode.component = createComponentInstance(
    initialVNode,
    parentComponent,
    parentSuspense
  ))

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

  // setupComponent setup: similar to vue2's new Vue() initializes this._init(options) in the vue2 constructor
  // Recall what you did with new Vue in VUe2
  // 1. User configuration options and system configuration options are combined
$parent $root $children $refs
  // 3. Listen for your own custom events
  // 4. Parse your own slot
  // 5. Also, it performs responsive processing on some internal data, such as props(properties) MethoSDS (methods) Data computed watch
    
// This is exactly what we're doing here
  setupComponent(instance)

  // 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
  }
  
  // Add render function side effects
  // The render function is used to retrieve the virtual DOM
  // The current component is updated and then re-patched
  setupRenderEffect(
    instance,
    initialVNode,
    container,
    anchor,
    parentSuspense,
    isSVG,
    optimized
  )
}
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Follow the process above to install setupComponent

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

  const { props, children } = instance.vnode
  const isStateful = isStatefulComponent(instance)
  / / processing props
  initProps(instance, props, isStateful, isSSR)
  // Process the slot
  initSlots(instance, children)

  const setupResult = isStateful
    // Data responsive processing
    ? setupStatefulComponent(instance, isSSR)
    : undefined
  isInSSRComponentSetup = false
  return setupResult
}
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SetupStatefulComponent Data reactive processing

function setupStatefulComponent(
  instance: ComponentInternalInstance,
  isSSR: boolean
) {
  // Since the initialization is passed in a vnode configured with obj conversion,
  // So type is the root component configuration object
  // createApp({
  // data() {
  // return { aa: 'haha' }
  / /},
      
  // The setup option and data(){return {}} can exist together, but setup takes precedence
  // setup() {
  // const aa = ref('haha')
  // return { aa }
  / /}
  // })
  const Component = instance.type as ComponentOptions

  // 0. create render proxy property access cache
  instance.accessCache = Object.create(null)

  // The root component configuration object does the proxy operation i.e. rendering function context, data responsive proxy
  // All future reactive data in the render function is retrieved from the proxy
  // const instance = getCurrentInstance(); You can get it in setup(){}
  // const { ctx, proxy } = instance
  / / PublicInstanceProxyHandlers will first to find attributes from the setup, if there is no will to find in the data
  instance.proxy = new Proxy(instance.ctx, PublicInstanceProxyHandlers)

  // call setup()
  // Handle the setup option
  // The setup option and data(){return {}} can exist together, but setup takes precedence
  / / PublicInstanceProxyHandlers will first to find attributes from the setup, if there is no will to find in the data
  const { setup } = Component
  if (setup) {
    const setupContext = (instance.setupContext =
      setup.length > 1 ? createSetupContext(instance) : null)

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

    if (isPromise(setupResult)) {
      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
      }
    } else {
      // The handleSetupResult method is finally called internally
      // finishComponentSetup(instance, isSSR)  
      handleSetupResult(instance, setupResult, isSSR)
    }
  } else {
   If setup is not present in createApp, go here
    finishComponentSetup(instance, isSSR)
  }
}
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Then look at the finishComponentSetup function

ApplyOptions (Instance, Component) is called internally, which is compatible with VUe2.0 processing

const {
    // composition
    mixins,
    extends: extendsOptions,
    // state
    data: dataOptions,
    computed: computedOptions,
    methods,
    watch: watchOptions,
    provide: provideOptions,
    inject: injectOptions,
    // assets
    components,
    directives,
    // lifecycle
    beforeMount,
    mounted,
    beforeUpdate,
    updated,
    activated,
    deactivated,
    beforeDestroy,
    beforeUnmount,
    destroyed,
    unmounted,
    render,
    renderTracked,
    renderTriggered,
    errorCaptured,
    // public API
    expose
  } = options
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When the components are installed, go to setupRenderEffect

// If the data inside the function changes, the function is re-executed
// There is no watcher here compared to VUe2
instance.update = effect(function componentEffect() {
  // Get the vNode of the current root component
  // Execute the render function to get the dom
  const subTree = (instance.subTree = renderComponentRoot(instance))
  // Initialize the patch
  // Since initialization is a Fragment
  // After the patch is removed, the nodes of and type will be processed internally and searched recursively
  patch(
    null,
    subTree, // Initialize with a Fragment
    container,
    anchor,
    instance,
    parentSuspense,
    isSVG
  )
})

// patch -> processFragment

const processFragment = (
  n1: VNode | null,
  n2: VNode,
  container: RendererElement,
  anchor: RendererNode | null,
  parentComponent: ComponentInternalInstance | null,
  parentSuspense: SuspenseBoundary | null,
  isSVG: boolean,
  slotScopeIds: string[] | null,
  optimized: boolean
) = > {
  // The old vnode passed a null during initialization
  // n2 new vNode sends subTree
  if (n1 == null) {
    hostInsert(fragmentStartAnchor, container, anchor)
    hostInsert(fragmentEndAnchor, container, anchor)
    // Mount the child node
    mountChildren(
      n2.children as VNodeArrayChildren,
      container,
      fragmentEndAnchor,
      parentComponent,
      parentSuspense,
      isSVG,
      slotScopeIds,
      optimized
    )
  }
}

// mountChildren Mounts the child node
const mountChildren: MountChildrenFn = (
  children,
  container,
  anchor,
  parentComponent,
  parentSuspense,
  isSVG,
  optimized,
  slotScopeIds,
  start = 0
) = > {
  // Perform patch processing on recursive child nodes
  // Initialization is complete
  // Patch will be processed according to the section type
  // Text tags, comments, etc
  for (let i = start; i < children.length; i++) {
    const child = (children[i] = optimized
      ? cloneIfMounted(children[i] as VNode)
      : normalizeVNode(children[i]))
    patch(
      null,
      child,
      container,
      anchor,
      parentComponent,
      parentSuspense,
      isSVG,
      optimized,
      slotScopeIds
    )
  }
}
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Register global methods

Stereotypes are available in Vue2, but not in Vue3

Provide/inject Dependency injection (officially recommended)

Vue3js. Cn/docs/useful/API…

// provide and inject enable dependency injection. Both can only be called during setup() using the current active instance.
import { ref, provide } from 'vue'
setup() {
    let title = ref('The value to be passed')
    // provide the first is the name, and the second value is the parameter that needs to be passed
    provide('title', title); 
    let setTitle = () = > {
         // There will be a response after clicking!
        title.value = 'When I click, the title will be this.';
    }
    return {
        title,
        setTitle
    }
}

/ / child component
import { inject } from 'vue'
setup() {
    // Inject takes the name of the provide
	let title = inject('title'); 
}

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App. Config. GlobalProperties in app mount before use

const app = createApp(App)
app.config.globalProperties.http = () = > {}
app.mount('#app')

import { ref, computed, watch, getCurrentInstance, onMounted } from "vue";
export default {
  components: {
  TestComp
  },
  setup( ) {
    // Get the context instance, CTX equals this of vue2
    // But CTX is not responsive
    // Proxy is reactive
    const { ctx, proxy } = getCurrentInstance(); 

    onMounted(() = > {
      // This works in the local environment, but the online environment will report an error
      console.log(ctx, "ctx")
      ctx.http()
      
      // This is the only way to use it
      constinstance = getCurrentInstance() instance.appContext.config.globalProperties.http() }); }};Copy the code

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Initializing vuE3 source code parsing

Vue3 source code analysis

Depend on the installation

Ready to debug

Entrance to the file

CreateApp method

To mount the disk, mount the disk

Register global methods

xxxx

xxxx

Initializing vuE3 source code parsing

Vue3 source code analysis

Depend on the installation

Ready to debug

Entrance to the file

CreateApp method

To mount the disk, mount the disk

Register global methods

xxxx

xxxx

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