How to check in a Vue component if a user is authenticated in Laravel?

Putting a script within blade file will throw Vue Warning. Let me answer "How to check in a Vue component if a user is authenticated in Laravel" and leave you with your Vuex complexity. Also this method is simpler.

So, in your controller:

public function index()
{
    return view('index')->with('auth_user',  auth()->user());
}

In your blade(main.blade.php):

<div class="container">
    <example-component :auth_user='@json($auth_user)'></example-component>
</div>

In your vue-component, get your props(ExampleComponent.vue):

<script>
export default {

  props: ['auth_user'],

  created () {
    console.log(this.auth_user)

  }
}
</script>

Returns null if user is not logged in

Use axios interceptors. You intercept the access denied http response code and then act accordingly.

window.axios.interceptors.response.use(function (response) {
    return response;
}, function (error) {
    if (419 === error.response.status) {
         location.reload();
    } else {
        //Something else you want to do or do nothing
    }
});

Usually from your controller, you pass the authenticated user object into the view which will then be stored in a javascript variable

Controller:

public function index()
{
    return view('index', [
        'auth_user' => Auth::user()
    ]);
}

You will know if a user is authenticated if it returns an object or null where null means no user is authenticated.

In your blade, assign the auth_user into a javascript variable:

<script>
    window.auth_user = {!! json_encode($auth_user); !!};
</script>

your vuex store object should atleast look like this:

{
    state: {
        user: null
    },
    mutations: {
        setAuthUser(state, user) {
            state.user = user;
        }
    },
    getters: {
        isLoggedIn(state) {
            return state.user !== null;
        }
    }
}

Then in your Vue root component, get the auth_user and save it into the store:

<script>
    export default {

        mounted() {
            this.$store.commit('setAuthUser', window.auth_user);
        }

    }
</script>

You now basically have a getter called this.$store.getters.isLoggedIn that you can use in your application for checking if a user is currently logged in.

e.g: