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Amelie Lamb
Amelie Lamb

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Vite.js - Lightning Fast Builds Powered by ES Modules

Vite (pronounced /vit/, like "veet") is a build tool that aims to provide a faster and leaner development experience for modern web projects. Created by Evan You, the author of popular frontend framework Vue.js, Vite leverages native ES Module imports to provide lightning fast server start up and hot module replacement (HMR).

In this post we'll take a deep dive into Vite, covering topics like:

  • What problems Vite aims to solve
  • How Vite works under the hood
  • Key features and benefits of Vite
  • Comparison to other build tools like Webpack
  • When and why you may want to use Vite
  • How to get started with Vite

By the end you'll have a solid understanding of what Vite is, what it does, and whether it may be a good fit for your next web project.

The Problem: Bundle Bloat and Slow Build Times
Over the past several years, build tools like Webpack have become an indispensable part of the modern web development workflow. They allow us to bundle together modules and assets, transform code, optimize files, and more.

However, as projects grow in size and complexity, these build tools can start to show pain points:

  • Slow Start up and Rebuild Times: For large projects, starting up or rebuilding the bundle can take several seconds to minutes. This really slows down development when you just want to iterate quickly.
  • Large Bundle Sizes: Webpack bundles end up containing a lot of code, including polyfills and libraries. This results in slower page load times.
  • Complex Configs: Tools like Webpack often require complex configuration to optimize performance and bundles.

Vite aims to solve these problems by offering a leaner and faster alternative to traditional bundlers.

How Vite Works

So how does Vite achieve such fast build times? The key is its usage of native ES Modules and esbuild.

When you run vite, it starts up a development server that serves your source files over native ES Modules. Modern browsers can natively resolve ES Module imports without bundling required.

For example, if you have:

// main.js
import { add } from './add.js'

// add.js
export function add(a, b) {
  return a + b
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The browser can natively import add.js without needing it be bundled together with main.js.

This avoids the expensive work of bundling modules together into a single file. It also allows the browser to cache each module separately, avoiding re-fetching unchanged modules when you modify a file.

For browsers that don't support native ESM (like IE11), Vite uses esbuild to efficiently bundle your code into a format those browsers can understand.

The end result is that you avoid the heavy bundle and optimization process during development. You get lightning fast startup and rebuild times.

Vite only performs full bundling when building for production.

Key Features and Benefits

With the raw ES Module import approach, Vite aims to provide a much faster and leaner development experience. Some of its major features and benefits:

Instant Server Start

Starting the dev server usually takes less than 100ms. This enables you to rapidly iterate.

Lightning Fast HMR

Hot module replacement (HMR) updates are extremely fast - often < 50ms.

On-Demand Code Splitting

Only code actually used during a particular request is included in the page. Unused code is not loaded unless explicitly imported. This keeps bundle sizes lean.

Native ESM Support

Vite enables directly using native ES Modules and TypeScript files in the browser without bundling.

Lean Config

Minimal configuration is required compared to tools like Webpack. Presets handle common needs.

CSS/JSON Importing

Import CSS and JSON files directly from JavaScript. Vite handles transforming and bundling.

Backed by esbuild

esbuild is used as a bundling backend. It is extremely fast compared to traditional bundlers.

Comparison to Webpack

How does Vite compare to traditional bundlers like Webpack?

  • Speed: Vite wins heavily here. It avoids bundling for development resulting in much faster start up and rebuild times.
  • Config: Vite requires minimal config while Webpack often needs complex, customized configuration.
  • Code Splitting: Vite - leveraging native ESM - provides more efficient, finer-grained code splitting out of the box.
  • HMR: Vite has exceptionally fast HMR with partial module updates. Webpack HMR updates can lag.
  • Browser Support: Webpack bundles code so older browsers are supported. Vite requires browsers with native ESM support.
  • Build Output: Webpack is still superior at producing optimized production bundles. But for development, Vite's output is comparable though not as optimized.

Hence, Vite shines for development. For production, traditional bundlers produce better optimized output. The recommendation is to use Vite for development and then use vite-plugin-bundle for optimized production building.

When to Use Vite

Here are some good cases where Vite is a great fit:

  • New projects where you want fast dev iterations and don't need IE11 support.
  • Existing projects currently using Webpack/Rollup that have become slower.
  • Building a component library - develop components faster.
  • Prototyping - quickly build and iterate on proof-of-concepts and experiments.

How to Install Vite.JS

  • Install Node.js if you don't already have it. Vite requires Node.js version 14.18+, 16+.
  • Create a new project folder and change into it:
mkdir my-vite-app
cd my-vite-app
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  • Initialize the project:
npm init @vitejs/app
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Select a framework (React, Preact, Vue, Svelte etc). This will setup the scaffolding.

Install dependencies:

npm install
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Start the dev server:

npm run dev
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Build for production:

npm run build
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That covers the main steps to get started with creating a Vite project with a UI framework. Refer to the Vite docs for more details on configuration options and commands.

Check this detailed guide to Install Vite.JS quickly.

Vite may NOT be the best fit when:

  • You need to support older browsers like IE11.
  • Your project has special needs that require fine-grained control over the final bundle.

    To start using Vite for your project:

  • Scaffold a new project with npm init vite@latest

  • Start the dev server with npm run dev

  • Modify source files and watch extremely fast live updates!

  • Build for production with npm run build

  • Preview the production build with npm run preview

  • Vite makes it this easy to get started and iterate quickly on modern web projects.

My Final Words on Vite.Js

Vite provides a next-generation frontend build tool experience. By leveraging native ESM and esbuild, it offers lightning fast HMR and minimal bundles during development.

The result is drastically shortened dev cycles. You can build and iterate on UI components faster than ever before.

While Vite is not a full replacement for optimized bundlers like Webpack, it represents the future of frontend tooling. The problems Vite solves will only become more pronounced as projects grow larger and more complex.

If you're starting a new project, especially if targeting modern browsers, give Vite a try. It may just become your new favorite dev workflow.

The future looks bright for frontend tooling. Balancing raw developer speed with production optimizations is a tough problem. Vite pushes the bar significantly forward. As it continues to mature, Vite promises to revolutionize the frontend development experience.

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