use const whenever possible

Author: yyx990803

src/directives/view.js

@@ -3,22 +3,22 @@ import { activate } from '../pipeline'
 
 export default function (Vue) {
 
-  let _ = Vue.util
-  let componentDef =
+  const _ = Vue.util
+  const componentDef =
     // 0.12
     Vue.directive('_component') ||
     // 1.0
     Vue.internalDirectives.component
   // <router-view> extends the internal component directive
-  let viewDef = _.extend({}, componentDef)
+  const viewDef = _.extend({}, componentDef)
 
   // with some overrides
   _.extend(viewDef, {
 
     _isRouterView: true,
 
     bind () {
-      let route = this.vm.$route
+      const route = this.vm.$route
       /* istanbul ignore if */
       if (!route) {
         warn(
@@ -52,7 +52,7 @@ export default function (Vue) {
         parentView.childView = this
       } else {
         // this is the root view!
-        let router = route.router
+        const router = route.router
         router._rootView = this
       }
 

src/history/hash.js

@@ -8,23 +8,23 @@ export default class HashHistory {
   }
 
   start () {
-    let self = this
+    const self = this
     this.listener = function () {
-      let path = location.hash
+      const path = location.hash
       let raw = path.replace(/^#!?/, '')
       // always
       if (raw.charAt(0) !== '/') {
         raw = '/' + raw
       }
-      let formattedPath = self.formatPath(raw)
+      const formattedPath = self.formatPath(raw)
       if (formattedPath !== path) {
         location.replace(formattedPath)
         return
       }
       // determine query
       // note it's possible to have queries in both the actual URL
       // and the hash fragment itself.
-      let query = location.search && path.indexOf('?') > -1
+      const query = location.search && path.indexOf('?') > -1
           ? '&' + location.search.slice(1)
           : location.search
       self.onChange(decodeURI(path.replace(/^#!?/, '') + query))
@@ -47,8 +47,8 @@ export default class HashHistory {
   }
 
   formatPath (path, append) {
-    let isAbsoloute = path.charAt(0) === '/'
-    let prefix = '#' + (this.hashbang ? '!' : '')
+    const isAbsoloute = path.charAt(0) === '/'
+    const prefix = '#' + (this.hashbang ? '!' : '')
     return isAbsoloute
       ? prefix + path
       : prefix + resolvePath(

src/history/html5.js

@@ -17,7 +17,7 @@ export default class HTML5History {
     }
     this.onChange = onChange
     // check base tag
-    let baseEl = document.querySelector('base')
+    const baseEl = document.querySelector('base')
     this.base = baseEl && baseEl.getAttribute('href')
   }
 
@@ -38,7 +38,7 @@ export default class HTML5History {
   }
 
   go (path, replace, append) {
-    let url = this.formatPath(path, append)
+    const url = this.formatPath(path, append)
     if (replace) {
       history.replaceState({}, '', url)
     } else {
@@ -52,8 +52,8 @@ export default class HTML5History {
       // then push new state
       history.pushState({}, '', url)
     }
-    let hashMatch = path.match(hashRE)
-    let hash = hashMatch && hashMatch[0]
+    const hashMatch = path.match(hashRE)
+    const hash = hashMatch && hashMatch[0]
     path = url
       // strip hash so it doesn't mess up params
       .replace(hashRE, '')

src/index.js

@@ -85,15 +85,15 @@ class Router {
     this._suppress = suppressTransitionError
 
     // create history object
-    let inBrowser = Vue.util.inBrowser
+    const inBrowser = Vue.util.inBrowser
     this.mode = (!inBrowser || this._abstract)
       ? 'abstract'
       : this._history
         ? 'html5'
         : 'hash'
 
-    let History = historyBackends[this.mode]
-    let self = this
+    const History = historyBackends[this.mode]
+    const self = this
     this.history = new History({
       root: root,
       hashbang: this._hashbang,
@@ -364,7 +364,7 @@ class Router {
     this._guardRecognizer.add([{
       path: path,
       handler: (match, query) => {
-        let realPath = mapParams(
+        const realPath = mapParams(
           mappedPath,
           match.params,
           query
@@ -409,8 +409,8 @@ class Router {
       return
     }
 
-    let currentRoute = this._currentRoute
-    let currentTransition = this._currentTransition
+    const currentRoute = this._currentRoute
+    const currentTransition = this._currentTransition
 
     if (currentTransition) {
       if (currentTransition.to.path === path) {
@@ -430,8 +430,8 @@ class Router {
     }
 
     // construct new route and transition context
-    let route = new Route(path, this)
-    let transition = new Transition(this, route, currentRoute)
+    const route = new Route(path, this)
+    const transition = new Transition(this, route, currentRoute)
 
     // current transition is updated right now.
     // however, current route will only be updated after the transition has
@@ -454,8 +454,8 @@ class Router {
     }
 
     // check global before hook
-    let beforeHooks = this._beforeEachHooks
-    let startTransition = () => {
+    const beforeHooks = this._beforeEachHooks
+    const startTransition = () => {
       transition.start(() => {
         this._postTransition(route, state, anchor)
       })
@@ -494,7 +494,7 @@ class Router {
 
   _onTransitionValidated (transition) {
     // set current route
-    let route = this._currentRoute = transition.to
+    const route = this._currentRoute = transition.to
     // update route context for all children
     if (this.app.$route !== route) {
       this.app.$route = route
@@ -524,14 +524,14 @@ class Router {
     // handle scroll positions
     // saved scroll positions take priority
     // then we check if the path has an anchor
-    let pos = state && state.pos
+    const pos = state && state.pos
     if (pos && this._saveScrollPosition) {
       Vue.nextTick(() => {
         window.scrollTo(pos.x, pos.y)
       })
     } else if (anchor) {
       Vue.nextTick(() => {
-        let el = document.getElementById(anchor.slice(1))
+        const el = document.getElementById(anchor.slice(1))
         if (el) {
           window.scrollTo(window.scrollX, el.offsetTop)
         }

src/pipeline.js

@@ -13,7 +13,7 @@ import {
  */
 
 export function canReuse (view, handler, transition) {
-  let component = view.childVM
+  const component = view.childVM
   if (!component || !handler) {
     return false
   }
@@ -22,7 +22,7 @@ export function canReuse (view, handler, transition) {
   if (view.Component !== handler.component) {
     return false
   }
-  let canReuseFn = getRouteConfig(component, 'canReuse')
+  const canReuseFn = getRouteConfig(component, 'canReuse')
   return typeof canReuseFn === 'boolean'
     ? canReuseFn
     : canReuseFn
@@ -41,8 +41,8 @@ export function canReuse (view, handler, transition) {
  */
 
 export function canDeactivate (view, transition, next) {
-  let fromComponent = view.childVM
-  let hook = getRouteConfig(fromComponent, 'canDeactivate')
+  const fromComponent = view.childVM
+  const hook = getRouteConfig(fromComponent, 'canDeactivate')
   if (!hook) {
     next()
   } else {
@@ -67,7 +67,7 @@ export function canActivate (handler, transition, next) {
       return
     }
     // determine if this component can be activated
-    let hook = getRouteConfig(Component, 'canActivate')
+    const hook = getRouteConfig(Component, 'canActivate')
     if (!hook) {
       next()
     } else {
@@ -87,8 +87,8 @@ export function canActivate (handler, transition, next) {
  */
 
 export function deactivate (view, transition, next) {
-  let component = view.childVM
-  let hook = getRouteConfig(component, 'deactivate')
+  const component = view.childVM
+  const hook = getRouteConfig(component, 'deactivate')
   if (!hook) {
     next()
   } else {
@@ -106,7 +106,7 @@ export function deactivate (view, transition, next) {
  */
 
 export function activate (view, transition, depth, cb, reuse) {
-  let handler = transition.activateQueue[depth]
+  const handler = transition.activateQueue[depth]
   if (!handler) {
     saveChildView(view)
     if (view._bound) {
@@ -116,16 +116,16 @@ export function activate (view, transition, depth, cb, reuse) {
     return
   }
 
-  let Component = view.Component = handler.component
-  let activateHook = getRouteConfig(Component, 'activate')
-  let dataHook = getRouteConfig(Component, 'data')
-  let waitForData = getRouteConfig(Component, 'waitForData')
+  const Component = view.Component = handler.component
+  const activateHook = getRouteConfig(Component, 'activate')
+  const dataHook = getRouteConfig(Component, 'data')
+  const waitForData = getRouteConfig(Component, 'waitForData')
 
   view.depth = depth
   view.activated = false
 
   let component
-  let loading = !!(dataHook && !waitForData)
+  const loading = !!(dataHook && !waitForData)
 
   // "reuse" is a flag passed down when the parent view is
   // either reused via keep-alive or as a child of a kept-alive view.
@@ -162,7 +162,7 @@ export function activate (view, transition, depth, cb, reuse) {
     // and also properly update current view's child view.
     if (view.keepAlive) {
       component.$loadingRouteData = loading
-      let cachedChildView = component._keepAliveRouterView
+      const cachedChildView = component._keepAliveRouterView
       if (cachedChildView) {
         view.childView = cachedChildView
         component._keepAliveRouterView = null
@@ -172,17 +172,17 @@ export function activate (view, transition, depth, cb, reuse) {
 
   // cleanup the component in case the transition is aborted
   // before the component is ever inserted.
-  let cleanup = () => {
+  const cleanup = () => {
     component.$destroy()
   }
 
   // actually insert the component and trigger transition
-  let insert = () => {
+  const insert = () => {
     if (reuse) {
       cb && cb()
       return
     }
-    let router = transition.router
+    const router = transition.router
     if (router._rendered || router._transitionOnLoad) {
       view.transition(component)
     } else {
@@ -201,7 +201,7 @@ export function activate (view, transition, depth, cb, reuse) {
   }
 
   // called after activation hook is resolved
-  let afterActivate = () => {
+  const afterActivate = () => {
     view.activated = true
     // activate the child view
     if (view.childView) {
@@ -234,8 +234,8 @@ export function activate (view, transition, depth, cb, reuse) {
  */
 
 export function reuse (view, transition) {
-  let component = view.childVM
-  let dataHook = getRouteConfig(component, 'data')
+  const component = view.childVM
+  const dataHook = getRouteConfig(component, 'data')
   if (dataHook) {
     loadData(component, transition, dataHook)
   }
@@ -266,10 +266,10 @@ function loadData (component, transition, hook, cb, cleanup) {
       }, Object.create(null))
     }
     // handle promise sugar syntax
-    let promises = []
+    const promises = []
     if (isPlainObject(data)) {
       Object.keys(data).forEach(key => {
-        let val = data[key]
+        const val = data[key]
         if (isPromise(val)) {
           promises.push(val.then(resolvedVal => {
             component.$set(key, resolvedVal)
@@ -312,7 +312,7 @@ function saveChildView (view) {
 
 /**
  * Check plain object.
- * 
+ *
  * @param {*} val
  */
 

src/route.js

@@ -10,7 +10,7 @@ const internalKeysRE = /^(component|subRoutes)$/
 export default class Route {
 
   constructor (path, router) {
-    let matched = router._recognizer.recognize(path)
+    const matched = router._recognizer.recognize(path)
     if (matched) {
       // copy all custom fields from route configs
       [].forEach.call(matched, match => {