fix: State not defined (#178)

* Fix state not defined without SSR.

* Add preserveState option.

* Add docs.

Fixes #173

docs/options-reference.md

@@ -58,7 +58,7 @@ Here are all the options available when configuring the module and their default
     cookieKey: 'i18n_redirected',
     // Set to always redirect to value stored in the cookie, not just once
     alwaysRedirect: false,
-    // If no locale for the browsers locale is a match, use this one as a fallback 
+    // If no locale for the browsers locale is a match, use this one as a fallback
     fallbackLocale: null
   },
 
@@ -84,15 +84,18 @@ Here are all the options available when configuring the module and their default
   vuex: {
     // Module namespace
     moduleName: 'i18n',
-    
+
     // Mutations config
     mutations: {
       // Mutation to commit to store current locale, set to false to disable
       setLocale: 'I18N_SET_LOCALE',
 
       // Mutation to commit to store current message, set to false to disable
       setMessages: 'I18N_SET_MESSAGES'
-    }
+    },
+
+    // PreserveState from server
+    preserveState: false
   },
 
   // By default, custom routes are extracted from page files using acorn parsing,

src/helpers/constants.js

@@ -46,7 +46,8 @@ exports.DEFAULT_OPTIONS = {
     mutations: {
       setLocale: 'I18N_SET_LOCALE',
       setMessages: 'I18N_SET_MESSAGES'
-    }
+    },
+    preserveState: false
   },
   parsePages: true,
   pages: {},

src/plugins/main.js

@@ -44,7 +44,7 @@ export default async ({ app, route, store, req }) => {
           state.messages = messages
         }
       }
-    })
+    }, { preserveState: vuex.preserveState })
   }
   <% } %>