vue2.7.16源码 - web runtimesrc/platforms/web/runtime/index.ts

src/platforms/web/runtime/index.ts - dom核心

dom核心,通过在core/index导出的Vue构造函数的基础上增强属性,实现$mount,开启和devtools的通信

import Vue from 'core/index'
import config from 'core/config'
import { extend, noop } from 'shared/util'
import { mountComponent } from 'core/instance/lifecycle'
import { devtools, inBrowser } from 'core/util/index'

import {
  query,
  mustUseProp,
  isReservedTag,
  isReservedAttr,
  getTagNamespace,
  isUnknownElement
} from 'web/util/index'

import { patch } from './patch'
import platformDirectives from './directives/index'
import platformComponents from './components/index'
import type { Component } from 'types/component'

// 插入一些web端的工具函数
Vue.config.mustUseProp = mustUseProp
Vue.config.isReservedTag = isReservedTag
Vue.config.isReservedAttr = isReservedAttr
Vue.config.getTagNamespace = getTagNamespace
Vue.config.isUnknownElement = isUnknownElement

// 预置model 和show 两个自定义指令
extend(Vue.options.directives, platformDirectives)

//预置 Transition TransitionGroup 两个全局组件
extend(Vue.options.components, platformComponents)

// 判断环境保留对应的dom创建函数
Vue.prototype.__patch__ = inBrowser ? patch : noop

// 组件挂载$mount函数
Vue.prototype.$mount = function (
  el?: string | Element,
  hydrating?: boolean
): Component {
  el = el && inBrowser ? query(el) : undefined
  return mountComponent(this, el, hydrating)
}

// 联动devtools
if (inBrowser) {
  setTimeout(() => {
    if (config.devtools) {
      if (devtools) {
        devtools.emit('init', Vue)
      } else if (__DEV__ && process.env.NODE_ENV !== 'test') {
        // @ts-expect-error
        console[console.info ? 'info' : 'log'](
          'Download the Vue Devtools extension for a better development experience:\n' +
            'https://github.com/vuejs/vue-devtools'
        )
      }
    }
    if (
      __DEV__ &&
      process.env.NODE_ENV !== 'test' &&
      config.productionTip !== false &&
      typeof console !== 'undefined'
    ) {
      // @ts-expect-error
      console[console.info ? 'info' : 'log'](
        `You are running Vue in development mode.\n` +
          `Make sure to turn on production mode when deploying for production.\n` +
          `See more tips at https://vuejs.org/guide/deployment.html`
      )
    }
  }, 0)
}

export default Vue

src/core/instance/lifecycle.ts - mountComponent实现, 挂载真实dom

export function mountComponent(
  vm: Component,
  el: Element | null | undefined,
  hydrating?: boolean
): Component {
  vm.$el = el
  // 没有render方法
  if (!vm.$options.render) {
    // 创建空的vnode
    vm.$options.render = createEmptyVNode
    if (__DEV__) {
      /* istanbul ignore if */
      if (
        (vm.$options.template && vm.$options.template.charAt(0) !== '#') ||
        vm.$options.el ||
        el
      ) {
        warn(
          'You are using the runtime-only build of Vue where the template ' +
            'compiler is not available. Either pre-compile the templates into ' +
            'render functions, or use the compiler-included build.',
          vm
        )
      } else {
        warn(
          'Failed to mount component: template or render function not defined.',
          vm
        )
      }
    }
  }
  // 触发beforeMount生命周期
  callHook(vm, 'beforeMount')

  let updateComponent
  /* istanbul ignore if */
  if (__DEV__ && config.performance && mark) {
    updateComponent = () => {
      const name = vm._name
      const id = vm._uid
      const startTag = `vue-perf-start:${id}`
      const endTag = `vue-perf-end:${id}`

      mark(startTag)
      const vnode = vm._render()
      mark(endTag)
      measure(`vue ${name} render`, startTag, endTag)

      mark(startTag)
      vm._update(vnode, hydrating)
      mark(endTag)
      measure(`vue ${name} patch`, startTag, endTag)
    }
  } else {
  // 更新dom节点
    updateComponent = () => {
      vm._update(vm._render(), hydrating)
    }
  }

// Watcher触发一次更新 触发 beforeUpdate 事件
  const watcherOptions: WatcherOptions = {
    before() {
      if (vm._isMounted && !vm._isDestroyed) {
        callHook(vm, 'beforeUpdate')
      }
    }
  }

  if (__DEV__) {
    watcherOptions.onTrack = e => callHook(vm, 'renderTracked', [e])
    watcherOptions.onTrigger = e => callHook(vm, 'renderTriggered', [e])
  }

  // 创建新的Watcher
  new Watcher(
    vm,
    updateComponent,
    noop,
    watcherOptions,
    true /* isRenderWatcher */
  )
  hydrating = false

  // 调用之前创建的Watcher
  const preWatchers = vm._preWatchers
  if (preWatchers) {
    for (let i = 0; i < preWatchers.length; i++) {
      preWatchers[i].run()
    }
  }

 // 节点更新完成 触发 mounted 生命周期
  if (vm.$vnode == null) {
    vm._isMounted = true
    callHook(vm, 'mounted')
  }
  return vm
}

src/core/vdom/vnode.ts - createEmptyVNode实现

src/platforms/web/runtime-with-compiler.ts

原型上$mount实现,包含模板编译执行,然后执行mountComponent,编译成真实dom,触发生命周期
mountComponent 会启动 renderWatcher 开始构建渲染

import config from 'core/config'
import { warn, cached } from 'core/util/index'
import { mark, measure } from 'core/util/perf'

import Vue from './runtime/index'
import { query } from './util/index'
import { compileToFunctions } from './compiler/index'
import {
  shouldDecodeNewlines,
  shouldDecodeNewlinesForHref
} from './util/compat'
import type { Component } from 'types/component'
import type { GlobalAPI } from 'types/global-api'

const idToTemplate = cached(id => {
  const el = query(id)
  return el && el.innerHTML
})

const mount = Vue.prototype.$mount
Vue.prototype.$mount = function (
  el?: string | Element,
  hydrating?: boolean
): Component {
  // 查找元素 没有找到创建一个 div
  el = el && query(el)

  /* istanbul ignore if */
  // 不能挂载到body
  if (el === document.body || el === document.documentElement) {
    __DEV__ &&
      warn(
        `Do not mount Vue to <html> or <body> - mount to normal elements instead.`
      )
    return this
  }

  const options = this.$options
  // 没有render函数 需要判断template
  if (!options.render) {
    let template = options.template
    if (template) {
      if (typeof template === 'string') {
      // 字符串话找对应节点 获取对应的html
        if (template.charAt(0) === '#') {
          template = idToTemplate(template)
          /* istanbul ignore if */
          if (__DEV__ && !template) {
            warn(
              `Template element not found or is empty: ${options.template}`,
              this
            )
          }
        }
      } else if (template.nodeType) {
      // 如果带有nodetype 直接获取innerHTML属性
        template = template.innerHTML
      } else {
        if (__DEV__) {
          warn('invalid template option:' + template, this)
        }
        return this
      }
    } else if (el) {
      // 目标元素获取html
      template = getOuterHTML(el)
    }
    if (template) {
      /* istanbul ignore if */
      if (__DEV__ && config.performance && mark) {
        mark('compile')
      }
     // 模板转成render函数 获取静态节点编译函数
      const { render, staticRenderFns } = compileToFunctions(
        template,
        {
          outputSourceRange: __DEV__,
          shouldDecodeNewlines,
          shouldDecodeNewlinesForHref,
          delimiters: options.delimiters,
          comments: options.comments
        },
        this
      )
      // 保存render函数
      options.render = render
      // 保存静态节点渲染函数
      options.staticRenderFns = staticRenderFns

      /* istanbul ignore if */
      if (__DEV__ && config.performance && mark) {
        mark('compile end')
        measure(`vue ${this._name} compile`, 'compile', 'compile end')
      }
    }
  }
  // 触发mountComponent
  return mount.call(this, el, hydrating)
}

/**
 * Get outerHTML of elements, taking care
 * of SVG elements in IE as well.
 */
function getOuterHTML(el: Element): string {
  if (el.outerHTML) {
    return el.outerHTML
  } else {
    const container = document.createElement('div')
    container.appendChild(el.cloneNode(true))
    return container.innerHTML
  }
}

// 保存模板编译函数
Vue.compile = compileToFunctions

export default Vue as GlobalAPI