laravel + vue router cannot get parameters from url

I try to get parameters from url

let's say url contains:

localhost:8000/blog?q=hello

I want to grab hello to trigger function call

What I had declare in app.js in laravel webpack:

import VueRouter from 'vue-router';
Vue.use(VueRouter);

const router = new VueRouter({
    mode: 'history',
    routes: []
})

const app = new Vue({
    router
});

export default app;

In blog page, I try to extract the parameter from url

new Vue ({
       el: "#blog-content",
   },

   mounted: function() {
       q = this.$route.query.q
       console.log(q)
   }
)

I npm run dev to compile and run the blog page it show error:

TypeError: Cannot read property 'query' of undefined

what is wrong? I am sure that Vue Router is properly installed in the application.

via Chebli Mohamed