VueJS - Code Splitting

Implementing Code Splitting in VueJS

Code splitting is a technique to split your application into smaller bundles that can be loaded on demand. This guide explores how to implement code splitting in VueJS to optimize the performance and load time of your applications.

Dynamic Imports

Dynamic imports allow you to import modules on demand. This is the core technique used for code splitting:

// main.js
import { createApp } from 'vue';
import App from './App.vue';
import router from './router';

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

// router/index.js
import { createRouter, createWebHistory } from 'vue-router';

const Home = () => import('@/views/Home.vue');
const About = () => import('@/views/About.vue');

const routes = [
  {
    path: '/',
    name: 'Home',
    component: Home
  },
  {
    path: '/about',
    name: 'About',
    component: About
  }
];

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

export default router;
                

Lazy Loading Components

Lazy loading components can be achieved using dynamic imports. This ensures that components are loaded only when they are needed:

// App.vue




// router/index.js
import { createRouter, createWebHistory } from 'vue-router';

const Home = () => import('@/views/Home.vue');
const About = () => import('@/views/About.vue');

const routes = [
  {
    path: '/',
    name: 'Home',
    component: Home
  },
  {
    path: '/about',
    name: 'About',
    component: About
  }
];

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

export default router;
                

Webpack Configuration for Code Splitting

Webpack supports code splitting out of the box. You can customize its configuration to optimize the bundle splitting:

// webpack.config.js
module.exports = {
  optimization: {
    splitChunks: {
      chunks: 'all',
      minSize: 20000,
      maxSize: 70000,
      minChunks: 1,
      maxAsyncRequests: 30,
      maxInitialRequests: 30,
      automaticNameDelimiter: '~',
      cacheGroups: {
        defaultVendors: {
          test: /[\\/]node_modules[\\/]/,
          priority: -10
        },
        default: {
          minChunks: 2,
          priority: -20,
          reuseExistingChunk: true
        }
      }
    }
  }
};
                

Prefetching and Preloading

Webpack also supports prefetching and preloading to improve the performance of lazy-loaded components:

// router/index.js
import { createRouter, createWebHistory } from 'vue-router';

const Home = () => import(/* webpackPrefetch: true */ '@/views/Home.vue');
const About = () => import(/* webpackPreload: true */ '@/views/About.vue');

const routes = [
  {
    path: '/',
    name: 'Home',
    component: Home
  },
  {
    path: '/about',
    name: 'About',
    component: About
  }
];

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

export default router;
                

Optimizing Bundle Size

In addition to code splitting, optimizing the bundle size can further enhance performance:

• Remove Unused Code: Use tools like PurgeCSS to remove unused CSS.
• Minify Assets: Minify JavaScript, CSS, and HTML files to reduce their size.
• Tree Shaking: Remove unused code from your JavaScript bundles using tree shaking.

// vue.config.js
module.exports = {
  configureWebpack: {
    optimization: {
      minimize: true,
      splitChunks: {
        chunks: 'all'
      }
    }
  }
};
                

Best Practices

Follow these best practices for implementing code splitting in VueJS applications:

• Use Dynamic Imports: Implement dynamic imports to load modules on demand.
• Lazy Load Components: Lazy load components to improve the initial load time.
• Optimize Webpack Configuration: Customize Webpack configuration to optimize bundle splitting and loading.
• Prefetch and Preload: Use prefetching and preloading to improve the performance of lazy-loaded components.
• Monitor and Analyze Bundles: Use tools like Webpack Bundle Analyzer to monitor and analyze your bundles.
• Optimize Bundle Size: Remove unused code, minify assets, and use tree shaking to reduce bundle size.

Summary

This guide provided an overview of implementing code splitting in VueJS, including using dynamic imports, lazy loading components, optimizing Webpack configuration, and following best practices. By leveraging code splitting, you can significantly improve the performance and load time of your VueJS applications.