Vue路由Hash模式分析

時間 2020-10-05

標籤 javascript html vue java node git github vue-router api 數組欄目系統網絡简体版

原文原文鏈接

Vue路由Hash模式分析

Vue-router是Vue的核心組件，主要是做爲Vue的路由管理器，Vue-router默認hash模式，即便用URL的Hash來模擬一個完整的URL，當URL改變時頁面不會從新加載。javascript

描述

Hash符號即#本來的目的是用來指示URL中指示網頁中的位置，例如https://www.example.com/index.html#print即表明example的index.html的print位置，瀏覽器讀取這個URL後，會自動將print位置滾動至可視區域，一般使用<a>標籤的name屬性或者<div>標籤的id屬性指定錨點。
經過window.location.hash屬性可以讀取錨點位置，能夠爲Hash的改變添加hashchange監聽事件，每一次改變Hash，都會在瀏覽器的訪問歷史中增長一個記錄，此外Hash雖然出如今URL中，但不會被包括在HTTP請求中，即#及以後的字符不會被髮送到服務端進行資源或數據的請求，其是用來指導瀏覽器動做的，對服務器端沒有效果，所以改變Hash不會從新加載頁面。
Vue-router的做用就是經過改變URL，在不從新請求頁面的狀況下，更新頁面視圖，從而動態加載與銷燬組件，簡單的說就是，雖然地址欄的地址改變了，可是並非一個全新的頁面，而是以前的頁面某些部分進行了修改，這也是SPA單頁應用的特色，其全部的活動侷限於一個Web頁面中，非懶加載的頁面僅在該Web頁面初始化時加載相應的HTML、JavaScript、CSS文件，一旦頁面加載完成，SPA不會進行頁面的從新加載或跳轉，而是利用JavaScript動態的變換HTML，默認Hash模式是經過錨點實現路由以及控制組件的顯示與隱藏來實現相似於頁面跳轉的交互。html

分析

Vue-router源碼的實現比較複雜，會處理各類兼容問題與異常以及各類條件分支，文章分析比較核心的代碼部分，精簡事後的版本，重要部分作出註釋，commit id爲560d11d。vue

首先是在定義Router時調用Vue.use(VueRouter)，此時會調用VueRouter類上的靜態方法，即VueRouter.install = install，install模塊主要是保證Vue-router只被use一次，以及經過mixin在Vue的生命週期beforeCreate內註冊實例，在destroyed內銷燬實例，還有定義$router與$route屬性爲只讀屬性以及<router-view>與<router-link>全局組件的註冊。java

// dev/src/install.js line 6
export function install (Vue) {
  if (install.installed && _Vue === Vue) return
  install.installed = true // 保證 Vue-router 只被 use 一次

  _Vue = Vue

  const isDef = v => v !== undefined

  const registerInstance = (vm, callVal) => {
    let i = vm.$options._parentVnode
    if (isDef(i) && isDef(i = i.data) && isDef(i = i.registerRouteInstance)) {
      i(vm, callVal)
    }
  }

  Vue.mixin({
    beforeCreate () { // 註冊實例
      if (isDef(this.$options.router)) { // this.$options.router 來自於 VueRouter 的實例化 // 判斷實例是否已經掛載
        this._routerRoot = this
        this._router = this.$options.router
        this._router.init(this) // // 調用 VueRouter 的 init 方法
        Vue.util.defineReactive(this, '_route', this._router.history.current)
      } else {
        this._routerRoot = (this.$parent && this.$parent._routerRoot) || this // 將組件的 _routerRoot 都指向根 Vue 實例
      }
      registerInstance(this, this)
    },
    destroyed () { // 銷燬實例 即掛載undefined
      registerInstance(this)
    }
  })

  Object.defineProperty(Vue.prototype, '$router', {
    get () { return this._routerRoot._router }
  })

  Object.defineProperty(Vue.prototype, '$route', {
    get () { return this._routerRoot._route }
  })

  Vue.component('RouterView', View) // 註冊全局組件 <router-view>
  Vue.component('RouterLink', Link) // 註冊全局組件 <router-link>

  const strats = Vue.config.optionMergeStrategies
  // use the same hook merging strategy for route hooks
  strats.beforeRouteEnter = strats.beforeRouteLeave = strats.beforeRouteUpdate = strats.created
}

以後是VueRouter對象的構造函數，主要是先獲取mode的值，若是mode的值爲history可是瀏覽器不支持history模式,那麼就強制設置mode值爲hash，接下來根據mode的值，來選擇vue-router使用哪一種模式。node

// dev/src/index.js line 40
constructor (options: RouterOptions = {}) {
  this.app = null
  this.apps = []
  this.options = options
  this.beforeHooks = []
  this.resolveHooks = []
  this.afterHooks = []
  this.matcher = createMatcher(options.routes || [], this) // 建立路由匹配對象

  let mode = options.mode || 'hash'
  this.fallback =
    mode === 'history' && !supportsPushState && options.fallback !== false // 檢車兼容
  if (this.fallback) {
    mode = 'hash'
  }
  if (!inBrowser) {
    mode = 'abstract'
  }
  this.mode = mode

  switch (mode) {
    case 'history':
      this.history = new HTML5History(this, options.base)
      break
    case 'hash':
      this.history = new HashHistory(this, options.base, this.fallback) // 實例化Hash模式
      break
    case 'abstract':
      this.history = new AbstractHistory(this, options.base)
      break
    default:
      if (process.env.NODE_ENV !== 'production') {
        assert(false, `invalid mode: ${mode}`)
      }
  }
}

在構造函數中調用了建立路由匹配對象的方法createMatcher，而在createMatcher中又調用了實際用以建立路由映射表的方法createRouteMap，能夠說createMatcher函數的做用就是建立路由映射表，而後經過閉包的方式讓addRoutes和match函數可以使用路由映射表的幾個對象，最後返回一個Matcher對象。git

// dev/src/create-matcher.js line 16
export function createMatcher (
  routes: Array<RouteConfig>,
  router: VueRouter
): Matcher {
  const { pathList, pathMap, nameMap } = createRouteMap(routes) // 建立路由映射表

  function addRoutes (routes) {
    createRouteMap(routes, pathList, pathMap, nameMap)
  }

  function match ( // 路由匹配
    raw: RawLocation,
    currentRoute?: Route,
    redirectedFrom?: Location
  ): Route {
    const location = normalizeLocation(raw, currentRoute, false, router) // location 是一個對象，相似於 {"_normalized":true,"path":"/","query":{},"hash":""}
    const { name } = location

    if (name) { // 若是有路由名稱 就進行nameMap映射
      const record = nameMap[name]  // nameMap[name] = 路由記錄
      if (process.env.NODE_ENV !== 'production') {
        warn(record, `Route with name '${name}' does not exist`)
      }
      if (!record) return _createRoute(null, location)
      const paramNames = record.regex.keys
        .filter(key => !key.optional)
        .map(key => key.name)

      if (typeof location.params !== 'object') {
        location.params = {}
      }

      if (currentRoute && typeof currentRoute.params === 'object') {
        for (const key in currentRoute.params) {
          if (!(key in location.params) && paramNames.indexOf(key) > -1) {
            location.params[key] = currentRoute.params[key]
          }
        }
      }

      location.path = fillParams(record.path, location.params, `named route "${name}"`)
      return _createRoute(record, location, redirectedFrom)
    } else if (location.path) { // 若是路由配置了path，到pathList和PathMap裏匹配到路由記錄 
      location.params = {}
      for (let i = 0; i < pathList.length; i++) {
        const path = pathList[i]
        const record = pathMap[path]
        if (matchRoute(record.regex, location.path, location.params)) {
          return _createRoute(record, location, redirectedFrom)
        }
      }
    }
    // no match
    return _createRoute(null, location)
  }

  function redirect ( // 處理重定向
    record: RouteRecord,
    location: Location
  ): Route {
    const originalRedirect = record.redirect
    let redirect = typeof originalRedirect === 'function'
      ? originalRedirect(createRoute(record, location, null, router))
      : originalRedirect

    if (typeof redirect === 'string') {
      redirect = { path: redirect }
    }

    if (!redirect || typeof redirect !== 'object') {
      if (process.env.NODE_ENV !== 'production') {
        warn(
          false, `invalid redirect option: ${JSON.stringify(redirect)}`
        )
      }
      return _createRoute(null, location)
    }

    const re: Object = redirect
    const { name, path } = re
    let { query, hash, params } = location
    query = re.hasOwnProperty('query') ? re.query : query
    hash = re.hasOwnProperty('hash') ? re.hash : hash
    params = re.hasOwnProperty('params') ? re.params : params

    if (name) {
      // resolved named direct
      const targetRecord = nameMap[name]
      if (process.env.NODE_ENV !== 'production') {
        assert(targetRecord, `redirect failed: named route "${name}" not found.`)
      }
      return match({
        _normalized: true,
        name,
        query,
        hash,
        params
      }, undefined, location)
    } else if (path) {
      // 1. resolve relative redirect
      const rawPath = resolveRecordPath(path, record)
      // 2. resolve params
      const resolvedPath = fillParams(rawPath, params, `redirect route with path "${rawPath}"`)
      // 3. rematch with existing query and hash
      return match({
        _normalized: true,
        path: resolvedPath,
        query,
        hash
      }, undefined, location)
    } else {
      if (process.env.NODE_ENV !== 'production') {
        warn(false, `invalid redirect option: ${JSON.stringify(redirect)}`)
      }
      return _createRoute(null, location)
    }
  }

  function alias ( // 處理別名
    record: RouteRecord,
    location: Location,
    matchAs: string
  ): Route {
    const aliasedPath = fillParams(matchAs, location.params, `aliased route with path "${matchAs}"`)
    const aliasedMatch = match({
      _normalized: true,
      path: aliasedPath
    })
    if (aliasedMatch) {
      const matched = aliasedMatch.matched
      const aliasedRecord = matched[matched.length - 1]
      location.params = aliasedMatch.params
      return _createRoute(aliasedRecord, location)
    }
    return _createRoute(null, location)
  }

  function _createRoute (  // 建立路由
    record: ?RouteRecord,
    location: Location,
    redirectedFrom?: Location
  ): Route {
    if (record && record.redirect) {
      return redirect(record, redirectedFrom || location)
    }
    if (record && record.matchAs) {
      return alias(record, location, record.matchAs)
    }
    return createRoute(record, location, redirectedFrom, router) // 建立路由對象
  }

  return {
    match,
    addRoutes
  }
}

// dev/src/create-route-map.js line 7
export function createRouteMap (
  routes: Array<RouteConfig>,
  oldPathList?: Array<string>,
  oldPathMap?: Dictionary<RouteRecord>,
  oldNameMap?: Dictionary<RouteRecord>
): {
  pathList: Array<string>,
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>
} {
  // the path list is used to control path matching priority
  const pathList: Array<string> = oldPathList || [] // 建立映射表
  // $flow-disable-line
  const pathMap: Dictionary<RouteRecord> = oldPathMap || Object.create(null)
  // $flow-disable-line
  const nameMap: Dictionary<RouteRecord> = oldNameMap || Object.create(null)

  routes.forEach(route => { // 遍歷路由配置，爲每一個配置添加路由記錄
    addRouteRecord(pathList, pathMap, nameMap, route)
  })

  // ensure wildcard routes are always at the end
  for (let i = 0, l = pathList.length; i < l; i++) { // 確保通配符在最後
    if (pathList[i] === '*') {
      pathList.push(pathList.splice(i, 1)[0])
      l--
      i--
    }
  }

  if (process.env.NODE_ENV === 'development') {
    // warn if routes do not include leading slashes
    const found = pathList
    // check for missing leading slash
      .filter(path => path && path.charAt(0) !== '*' && path.charAt(0) !== '/')

    if (found.length > 0) {
      const pathNames = found.map(path => `- ${path}`).join('\n')
      warn(false, `Non-nested routes must include a leading slash character. Fix the following routes: \n${pathNames}`)
    }
  }

  return {
    pathList,
    pathMap,
    nameMap
  }
}

function addRouteRecord ( // 添加路由記錄
  pathList: Array<string>,
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>,
  route: RouteConfig,
  parent?: RouteRecord,
  matchAs?: string
) {
  const { path, name } = route // 得到路由配置下的屬性
  if (process.env.NODE_ENV !== 'production') {
    assert(path != null, `"path" is required in a route configuration.`)
    assert(
      typeof route.component !== 'string',
      `route config "component" for path: ${String(
        path || name
      )} cannot be a ` + `string id. Use an actual component instead.`
    )
  }

  const pathToRegexpOptions: PathToRegexpOptions =
    route.pathToRegexpOptions || {}
  const normalizedPath = normalizePath(path, parent, pathToRegexpOptions.strict)

  if (typeof route.caseSensitive === 'boolean') {
    pathToRegexpOptions.sensitive = route.caseSensitive
  }

  const record: RouteRecord = { // 生成記錄對象
    path: normalizedPath,
    regex: compileRouteRegex(normalizedPath, pathToRegexpOptions),
    components: route.components || { default: route.component },
    instances: {},
    name,
    parent,
    matchAs,
    redirect: route.redirect,
    beforeEnter: route.beforeEnter,
    meta: route.meta || {},
    props:
      route.props == null
        ? {}
        : route.components
          ? route.props
          : { default: route.props }
  }

  if (route.children) { 
    // Warn if route is named, does not redirect and has a default child route.
    // If users navigate to this route by name, the default child will
    // not be rendered (GH Issue #629)
    if (process.env.NODE_ENV !== 'production') {
      if (
        route.name &&
        !route.redirect &&
        route.children.some(child => /^\/?$/.test(child.path))
      ) {
        warn(
          false,
          `Named Route '${route.name}' has a default child route. ` +
            `When navigating to this named route (:to="{name: '${
              route.name
            }'"), ` +
            `the default child route will not be rendered. Remove the name from ` +
            `this route and use the name of the default child route for named ` +
            `links instead.`
        )
      }
    }
    route.children.forEach(child => { // 遞歸路由配置的 children 屬性，添加路由記錄
      const childMatchAs = matchAs
        ? cleanPath(`${matchAs}/${child.path}`)
        : undefined
      addRouteRecord(pathList, pathMap, nameMap, child, record, childMatchAs)
    })
  }

  if (!pathMap[record.path]) { // 若是有多個相同的路徑，只有第一個起做用，後面的會被忽略
    pathList.push(record.path)
    pathMap[record.path] = record
  }

  if (route.alias !== undefined) { // 若是路由有別名的話，給別名也添加路由記錄
    const aliases = Array.isArray(route.alias) ? route.alias : [route.alias]
    for (let i = 0; i < aliases.length; ++i) {
      const alias = aliases[i]
      if (process.env.NODE_ENV !== 'production' && alias === path) {
        warn(
          false,
          `Found an alias with the same value as the path: "${path}". You have to remove that alias. It will be ignored in development.`
        )
        // skip in dev to make it work
        continue
      }

      const aliasRoute = {
        path: alias,
        children: route.children
      }
      addRouteRecord(
        pathList,
        pathMap,
        nameMap,
        aliasRoute,
        parent,
        record.path || '/' // matchAs
      )
    }
  }

  if (name) {
    if (!nameMap[name]) {
      nameMap[name] = record
    } else if (process.env.NODE_ENV !== 'production' && !matchAs) {
      warn(
        false,
        `Duplicate named routes definition: ` +
          `{ name: "${name}", path: "${record.path}" }`
      )
    }
  }
}

在上文的構造函數中實例化的HashHistory對象就是對於Hash模式下的路由的處理，主要是經過繼承History對象以及自身實現的方法完成路由，以及針對於不支持history api的兼容處理，以及保證默認進入的時候對應的Hash值是以/開頭的，若是不是則替換。在初始化VueRouter時調用的init方法調用了路由切換以及調用了setupListeners方法實現了路由的切換的監聽回調，注意此時並無在HashHistory對象的構造函數中直接添加事件監聽，這是爲了修復vuejs/vue-router#725的問題，簡要來講就是說若是在beforeEnter這樣的鉤子函數中是異步的話，beforeEnter鉤子就會被觸發兩次，緣由是由於在初始化的時候若是此時的hash值不是以/開頭的話就會補上#/，這個過程會觸發hashchange事件，因此會再走一次生命週期鉤子，也就意味着會再次調用beforeEnter鉤子函數。github

// dev/src/index.js line 21
export default class VueRouter {
  //...
  init (app: any /* Vue component instance */) {
    process.env.NODE_ENV !== 'production' &&
      assert(
        install.installed,
        `not installed. Make sure to call \`Vue.use(VueRouter)\` ` +
          `before creating root instance.`
      )

    this.apps.push(app)

    // set up app destroyed handler
    // https://github.com/vuejs/vue-router/issues/2639
    app.$once('hook:destroyed', () => {
      // clean out app from this.apps array once destroyed
      const index = this.apps.indexOf(app)
      if (index > -1) this.apps.splice(index, 1)
      // ensure we still have a main app or null if no apps
      // we do not release the router so it can be reused
      if (this.app === app) this.app = this.apps[0] || null

      if (!this.app) this.history.teardown()
    })

    // main app previously initialized
    // return as we don't need to set up new history listener
    if (this.app) {
      return
    }

    this.app = app

    const history = this.history

    if (history instanceof HTML5History || history instanceof HashHistory) {
      const handleInitialScroll = routeOrError => {
        const from = history.current
        const expectScroll = this.options.scrollBehavior
        const supportsScroll = supportsPushState && expectScroll

        if (supportsScroll && 'fullPath' in routeOrError) {
          handleScroll(this, routeOrError, from, false)
        }
      }
      const setupListeners = routeOrError => {
        history.setupListeners() // 初始化添加事件監聽
        handleInitialScroll(routeOrError)
      }
      history.transitionTo( // 若是默認頁，須要根據當前瀏覽器地址欄裏的 path 或者 hash 來激活對應的路由
        history.getCurrentLocation(),
        setupListeners,
        setupListeners
      )
    }

    history.listen(route => {
      this.apps.forEach(app => {
        app._route = route
      })
    })
  }
  //...
}

// dev/src/history/base.js line 24
export class History {
  // ...

  transitionTo (
    location: RawLocation,
    onComplete?: Function,
    onAbort?: Function
  ) {
    let route
    // catch redirect option https://github.com/vuejs/vue-router/issues/3201
    try {
      route = this.router.match(location, this.current) // // 獲取匹配的路由信息
    } catch (e) {
      this.errorCbs.forEach(cb => {
        cb(e)
      })
      // Exception should still be thrown
      throw e
    }
    const prev = this.current
    this.confirmTransition( // 確認跳轉
      route,
      () => {
        this.updateRoute(route) // 更新當前 route 對象
        onComplete && onComplete(route)
        this.ensureURL() // 子類實現的更新url地址 對於 hash 模式的話 就是更新 hash 的值
        this.router.afterHooks.forEach(hook => {
          hook && hook(route, prev)
        })

        // fire ready cbs once
        if (!this.ready) {
          this.ready = true
          this.readyCbs.forEach(cb => {
            cb(route)
          })
        }
      },
      err => {
        if (onAbort) {
          onAbort(err)
        }
        if (err && !this.ready) {
          // Initial redirection should not mark the history as ready yet
          // because it's triggered by the redirection instead
          // https://github.com/vuejs/vue-router/issues/3225
          // https://github.com/vuejs/vue-router/issues/3331
          if (!isNavigationFailure(err, NavigationFailureType.redirected) || prev !== START) {
            this.ready = true
            this.readyErrorCbs.forEach(cb => {
              cb(err)
            })
          }
        }
      }
    )
  }

  confirmTransition (route: Route, onComplete: Function, onAbort?: Function) {
    const current = this.current
    this.pending = route
    const abort = err => {
      // changed after adding errors with
      // https://github.com/vuejs/vue-router/pull/3047 before that change,
      // redirect and aborted navigation would produce an err == null
      if (!isNavigationFailure(err) && isError(err)) {
        if (this.errorCbs.length) {
          this.errorCbs.forEach(cb => {
            cb(err)
          })
        } else {
          warn(false, 'uncaught error during route navigation:')
          console.error(err)
        }
      }
      onAbort && onAbort(err)
    }
    const lastRouteIndex = route.matched.length - 1
    const lastCurrentIndex = current.matched.length - 1
    if (
      isSameRoute(route, current) && // 若是是相同的路由就不跳轉
      // in the case the route map has been dynamically appended to
      lastRouteIndex === lastCurrentIndex &&
      route.matched[lastRouteIndex] === current.matched[lastCurrentIndex]
    ) {
      this.ensureURL()
      return abort(createNavigationDuplicatedError(current, route))
    }

    const { updated, deactivated, activated } = resolveQueue( // 經過對比路由解析出可複用的組件，須要渲染的組件，失活的組件
      this.current.matched,
      route.matched
    )

    const queue: Array<?NavigationGuard> = [].concat( // 導航守衛數組
      // in-component leave guards
      extractLeaveGuards(deactivated),  // 失活的組件鉤子
      // global before hooks
      this.router.beforeHooks, // 全局 beforeEach 鉤子
      // in-component update hooks
      extractUpdateHooks(updated), // 在當前路由改變，可是該組件被複用時調用
      // in-config enter guards
      activated.map(m => m.beforeEnter), // 須要渲染組件 enter 守衛鉤子
      // async components
      resolveAsyncComponents(activated) // 解析異步路由組件
    )

    const iterator = (hook: NavigationGuard, next) => {
      if (this.pending !== route) { // 路由不相等就不跳轉路由
        return abort(createNavigationCancelledError(current, route))
      }
      try {
        hook(route, current, (to: any) => { // 只有執行了鉤子函數中的next，纔會繼續執行下一個鉤子函數，不然會暫停跳轉，如下邏輯是在判斷 next() 中的傳參
          if (to === false) {
            // next(false) -> abort navigation, ensure current URL
            this.ensureURL(true)
            abort(createNavigationAbortedError(current, route))
          } else if (isError(to)) {
            this.ensureURL(true)
            abort(to)
          } else if (
            typeof to === 'string' ||
            (typeof to === 'object' &&
              (typeof to.path === 'string' || typeof to.name === 'string'))
          ) {
            // next('/') or next({ path: '/' }) -> redirect
            abort(createNavigationRedirectedError(current, route))
            if (typeof to === 'object' && to.replace) {
              this.replace(to)
            } else {
              this.push(to)
            }
          } else {
            // confirm transition and pass on the value
            next(to)
          }
        })
      } catch (e) {
        abort(e)
      }
    }
    // ...
  }
  // ...
}

// dev/src/history/hash.js line 10
export class HashHistory extends History {
  constructor (router: Router, base: ?string, fallback: boolean) {
    super(router, base)
    // check history fallback deeplinking
    if (fallback && checkFallback(this.base)) {
      return
    }
    ensureSlash()
  }

  // this is delayed until the app mounts
  // to avoid the hashchange listener being fired too early
  setupListeners () { // 初始化 這將延遲到mounts生命週期 以免過早觸發hashchange偵聽器
    if (this.listeners.length > 0) {
      return
    }

    const router = this.router
    const expectScroll = router.options.scrollBehavior
    const supportsScroll = supportsPushState && expectScroll

    if (supportsScroll) {
      this.listeners.push(setupScroll())
    }

    const handleRoutingEvent = () => {
      const current = this.current
      if (!ensureSlash()) {
        return
      }
      this.transitionTo(getHash(), route => {
        if (supportsScroll) {
          handleScroll(this.router, route, current, true)
        }
        if (!supportsPushState) {
          replaceHash(route.fullPath)
        }
      })
    }
    const eventType = supportsPushState ? 'popstate' : 'hashchange'
    window.addEventListener(
      eventType,
      handleRoutingEvent
    )
    this.listeners.push(() => {
      window.removeEventListener(eventType, handleRoutingEvent)
    })
  }

  push (location: RawLocation, onComplete?: Function, onAbort?: Function) {
    const { current: fromRoute } = this
    this.transitionTo(
      location,
      route => {
        pushHash(route.fullPath)
        handleScroll(this.router, route, fromRoute, false)
        onComplete && onComplete(route)
      },
      onAbort
    )
  }

  replace (location: RawLocation, onComplete?: Function, onAbort?: Function) {
    const { current: fromRoute } = this
    this.transitionTo(
      location,
      route => {
        replaceHash(route.fullPath)
        handleScroll(this.router, route, fromRoute, false)
        onComplete && onComplete(route)
      },
      onAbort
    )
  }

  go (n: number) {
    window.history.go(n)
  }

  ensureURL (push?: boolean) {
    const current = this.current.fullPath
    if (getHash() !== current) {
      push ? pushHash(current) : replaceHash(current)
    }
  }

  getCurrentLocation () {
    return getHash()
  }
}

每日一題

https://github.com/WindrunnerMax/EveryDay

參考

https://router.vuejs.org/zh/
https://github.com/DDFE/DDFE-blog/issues/9
https://juejin.im/post/6844903647378145294
https://juejin.im/post/6844904062698127367
https://juejin.im/post/6844904018519523335
https://juejin.im/post/6844904012630720526
https://blog.csdn.net/zlingyun/article/details/83536589
https://ustbhuangyi.github.io/vue-analysis/v2/vue-router/install.html#vue-use
https://liyucang-git.github.io/2019/08/15/vue-router%E6%BA%90%E7%A0%81%E5%88%86%E6%9E%90/