feat(plugin): support runtimeConfig (#81)

Author: SkyaTura

README.md

@@ -45,6 +45,28 @@ export default {
 }
 ```
 
+### Runtime Config
+
+You can use [runtime config](https://nuxtjs.org/guide/runtime-config) if need to use dynamic environment variables in production. Otherwise, the options will be hardcoded during the build and won't be read from `nuxt.config` anymore.
+
+```js
+export default {
+  buildModules: [
+    '@nuxtjs/google-analytics'
+  ],
+
+  googleAnalytics: {
+    id: 'UA-12301-2', // Used as fallback if no runtime config is provided
+  },
+
+  publicRuntimeConfig: {
+    googleAnalytics: {
+      id: process.env.GOOGLE_ANALYTICS_ID
+    }
+  },
+}
+```
+
 ## Usage
 
 Click [here](https://matteogabriele.gitbooks.io/vue-analytics/) for all options and features of vue-analytics

lib/plugin.js

@@ -2,7 +2,9 @@ import Vue from 'vue'
 import VueAnalytics from 'vue-analytics'
 
 export default async (ctx, inject) => {
-  const options = <%= serialize(options) %>
+  const runtimeConfig = ctx.$config && ctx.$config.googleAnalytics || {}
+  const moduleOptions = <%= serialize(options) %>
+  const options = {...moduleOptions, ...runtimeConfig}
 
   if (typeof options.asyncID === 'function') {
     options.id = await options.asyncID(ctx)