refactor: remove circular dependency

src/util/push-state.js

@@ -2,40 +2,24 @@
 
 import { inBrowser } from './dom'
 import { saveScrollPosition } from './scroll'
+import { genStateKey, setStateKey, getStateKey } from './state-key'
+
+export const supportsPushState =
+ inBrowser &&
+ (function () {
+ const ua = window.navigator.userAgent
+
+ if (
+ (ua.indexOf('Android 2.') !== -1 || ua.indexOf('Android 4.0') !== -1) &&
+ ua.indexOf('Mobile Safari') !== -1 &&
+ ua.indexOf('Chrome') === -1 &&
+ ua.indexOf('Windows Phone') === -1
+ ) {
+ return false
+ }
 
-export const supportsPushState = inBrowser && (function () {
- const ua = window.navigator.userAgent
-
- if (
- (ua.indexOf('Android 2.') !== -1 || ua.indexOf('Android 4.0') !== -1) &&
- ua.indexOf('Mobile Safari') !== -1 &&
- ua.indexOf('Chrome') === -1 &&
- ua.indexOf('Windows Phone') === -1
- ) {
- return false
- }
-
- return window.history && 'pushState' in window.history
-})()
-
-// use User Timing api (if present) for more accurate key precision
-const Time = inBrowser && window.performance && window.performance.now
- ? window.performance
- : Date
-
-let _key: string = genKey()
-
-function genKey (): string {
- return Time.now().toFixed(3)
-}
-
-export function getStateKey () {
- return _key
-}
-
-export function setStateKey (key: string) {
- _key = key
-}
+ return window.history && 'pushState' in window.history
+ })()
 
 export function pushState (url?: string, replace?: boolean) {
  saveScrollPosition()
@@ -44,10 +28,9 @@ export function pushState (url?: string, replace?: boolean) {
  const history = window.history
  try {
  if (replace) {
- history.replaceState({ key: _key }, '', url)
+ history.replaceState({ key: getStateKey() }, '', url)
  } else {
- _key = genKey()
- history.pushState({ key: _key }, '', url)
+ history.pushState({ key: setStateKey(genStateKey()) }, '', url)
  }
  } catch (e) {
  window.location[replace ? 'replace' : 'assign'](url)

src/util/scroll.js

@@ -2,7 +2,7 @@
 
 import type Router from '../index'
 import { assert } from './warn'
-import { getStateKey, setStateKey } from './push-state'
+import { getStateKey, setStateKey } from './state-key'
 
 const positionStore = Object.create(null)
 

src/util/state-key.js

@@ -0,0 +1,22 @@
+/* @flow */
+import { inBrowser } from './dom'
+
+// use User Timing api (if present) for more accurate key precision
+const Time =
+ inBrowser && window.performance && window.performance.now
+ ? window.performance
+ : Date
+
+export function genStateKey (): string {
+ return Time.now().toFixed(3)
+}
+
+let _key: string = genStateKey()
+
+export function getStateKey () {
+ return _key
+}
+
+export function setStateKey (key: string) {
+ return (_key = key)
+}