vue3-middleware

Vue3 Middleware

vue3-middleware is a lightweight plugin for Vue 3 applications that provides middleware functionality. It allows you to add middleware functions that run before each navigation, providing a powerful tool for handling authentication, authorization, logging, and other concerns. With just a few simple steps, you can add this plugin to your vue application.

Installation

You can install vue3-middleware using npm or yarn.

Please note that this plugin currently support only vue 3.x and vue-router 4.x

# install using npm
npm install vue3-middleware

# or with yarn
yarn add vue3-middleware

Usage

Setting Up Middleware

First, you need to set up the middleware in your Vue 3 application. Import createMiddleware from vue3-middleware and set it up in your main application file (typically main.js or main.ts).

createMiddleware requires the router instance as its first argument — it's passed explicitly rather than read off the app, because that avoids relying on app.use(router) having already run (an ordering issue that's easy to hit in SSR entry files where the app/router are constructed fresh per request).

Note: Registered global middlewares will run for every navigation.

import { createApp } from "vue";
import App from './App.vue';
import { createMiddleware } from "vue3-middleware";
import removeTrailingSlash from './middlewares/removeTrailingSlash';
import router from './router';

const app = createApp(App);
const middleware = createMiddleware(router);

// OR with options
// const middleware = createMiddleware(router, {
//     global: [
//         removeTrailingSlash
//     ],
//     // OR
//     // global: removeTrailingSlash
// });

// Registration here
app.use(middleware);

// OR register with options
// app.use(middleware, {
//     global: [
//         removeTrailingSlash
//     ],
//     // OR
//     // global: removeTrailingSlash
// });

app.use(router);

app.mount('#app');

Defining Middleware

You can define middleware functions that will be executed before route changes. Middleware functions receive a context with to, from, isServer, next, cancel, redirect and externalRedirect, similar to Vue Router navigation guards.

Important: if a middleware calls cancel(), redirect() or externalRedirect(), you must return the result. These calls don't take effect on their own — the return value is what tells the middleware chain (and vue-router) what to do. Calling one without returning it is a common footgun; by default the plugin warns via console.warn in development when it detects this (see warnOnMissingReturn below).

You can optionally wrap middleware in the defineMiddleware helper — it's purely for type inference and does nothing at runtime.

// middleware/auth.ts
import { useUser } from '@/stores/user.ts';
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ to, next, redirect }) => {
    const user = useUser();
    if (to.meta.requiresAuth && !user.isLoggedIn) {
        return redirect({ name: 'login' });
    }
    return next();
});


// middleware/guest.ts
import { useUser } from '@/stores/user.ts';
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ from, next, redirect }) => {
    const user = useUser();
    if (user.isLoggedIn) {
        return redirect(from);
    }
    return next();
});


// middleware/removeTrailingSlash.ts
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ to, next, redirect }) => {
    if (to.path.length > 1 && to.path.endsWith("/")) {
        return redirect(to.path.substring(0, to.path.length - 1));
    }
    return next();
});


// middleware/noLeaveNoTransfer.ts
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ cancel }) => {
    // Explicitly cancel the navigation and terminate
    return cancel();
});

redirect performs an internal (same-app) redirect resolved by vue-router, and can't navigate cross-origin. For cross-origin / full-page redirects, use externalRedirect(url, status?) instead — in the browser it sets window.location.href; during SSR it calls the onExternalRedirect handler you provide to createMiddleware (see Options below).

Applying Middleware to Routes

You can apply middleware to specific routes by using the meta property in your route definitions.

import { createRouter, createWebHistory } from 'vue-router';
import Home from './views/Home.vue';
import Login from './views/Login.vue';
import auth from './middleware/auth';
import guest from './middlewares/guest';
import admin from './middlewares/admin';

const routes = [
    {
        path: '/',
        name: 'home',
        component: Home
    },
    {
        path: '/login',
        name: 'login',
        component: Login,
        meta: {
            middlewares: [guest],
            // OR
            // middlewares: guest
        }
    },
    {
        path: '/dashboard',
        name: 'dashboard',
        component: () => import('./views/Dashboard.vue'),
        meta: {
            middlewares: [auth]
        }
    },
    {
        path: '/admin',
        name: 'admin',
        redirect: {name: 'admin.dashboard'},
        meta: {
            middlewares: [auth, admin]
        }, 
        children: [
            {
                path: 'dashboard',
                name: 'admin.dashboard',
                component: () => import('./views/admin/Dashboard.vue'),
            },
            {
                path: 'users',
                name: 'admin.users',
                component: () => import('./views/admin/Users.vue'),
            }
        ]
    }
];

const router = createRouter({
    history: createWebHistory(),
    routes
});

export default router;

Note: A middleware that's defined on parent route will also guard children routes, so no you don't have to define it again on the children routes.

Options

createMiddleware(router, options) (and the second argument to app.use(middleware, options)) accepts:

Options passed to createMiddleware(router, options) and to app.use(middleware, options) are merged — global middlewares are concatenated, extra is shallow-merged, and the rest fall back from the app.use options to the createMiddleware options.

Typed extra context

If you use the extra option, pass its type as a generic to createMiddleware and defineMiddleware so it's available on context with full type-safety:

// main.ts
import { createMiddleware } from 'vue3-middleware';
import router from './router';

type ExtraContext = { userId: string | null };

const middleware = createMiddleware<ExtraContext>(router, {
    extra: { userId: null },
});

// middleware/auth.ts
import { defineMiddleware } from 'vue3-middleware';

type ExtraContext = { userId: string | null };

export default defineMiddleware<ExtraContext>(({ userId, next, redirect }) => {
    if (!userId) {
        return redirect({ name: 'login' });
    }
    return next();
});

Example

Here's a full example that combines the setup, middleware definition, and route application.

// main.ts
import { createApp } from "vue";
import App from './App.vue';
import { createMiddleware } from "vue3-middleware";
import removeTrailingSlash from './middlewares/removeTrailingSlash';
import router from './router';

const app = createApp(App);
const middleware = createMiddleware(router);

app.use(middleware, {
    global: [
        removeTrailingSlash
    ],
});

app.use(router);
app.mount('#app')


// middleware/auth.ts
import { useUser } from '@/stores/user.ts';
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ to, next, redirect }) => {
    const user = useUser();
    if (to.meta.requiresAuth && !user.isLoggedIn) {
        return redirect({ name: 'login' });
    }
    return next();
});


// middleware/guest.ts
import { useUser } from '@/stores/user.ts';
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ from, next, redirect }) => {
    const user = useUser();
    if (user.isLoggedIn) {
        return redirect(from);
    }
    return next();
});


// middleware/removeTrailingSlash.ts
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ to, next, redirect }) => {
    if (to.path.length > 1 && to.path.endsWith("/")) {
        return redirect(to.path.substring(0, to.path.length - 1));
    }
    return next();
});


// middleware/noLeaveNoTransfer.ts
import { defineMiddleware } from 'vue3-middleware';

export default defineMiddleware(({ cancel }) => {
    return cancel();
});


// router/index.ts
import { createRouter, createWebHistory } from 'vue-router';
import Home from './views/Home.vue';
import Login from './views/Login.vue';
import auth from './middleware/auth';
import guest from './middlewares/guest';
import admin from './middlewares/admin';

const routes = [
    {
        path: '/',
        name: 'home',
        component: Home
    },
    {
        path: '/login',
        name: 'login',
        component: Login,
        meta: {
            middlewares: [guest],
        }
    },
    {
        path: '/dashboard',
        name: 'dashboard',
        component: () => import('./views/Dashboard.vue'),
        meta: {
            middlewares: [auth]
        }
    },
    {
        path: '/admin',
        name: 'admin',
        redirect: {name: 'admin.dashboard'},
        meta: {
            middlewares: [auth, admin]
        }, 
        children: [
            {
                path: 'dashboard',
                name: 'admin.dashboard',
                component: () => import('./views/admin/Dashboard.vue'),
            },
            {
                path: 'users',
                name: 'admin.users',
                component: () => import('./views/admin/Users.vue'),
            }
        ]
    }
];

const router = createRouter({
    history: createWebHistory(),
    routes
});

export default router;

Contributing

Contributions are welcome! Please feel free to fork this package and contribute by submitting a pull request to enhance the functionalities.

How can I thank you?

Why not star the github repo? I'd love the attention! Why not share the link for this repository on X (formerly Twitter) or HackerNews? Spread the word!

Don't forget to follow me on X (formerly Twitter)! and also follow me on LinkedIn!

Thanks! Jacob Eke.

License

The MIT License (MIT). Please see License File for more information.