What Is Vite? Why Use Vite? What Problems Does It Solve?

What Is Vite?

In recent years, Vite has become a hot topic in the front-end world. It's a build tool that significantly streamlines and speeds up the process of building front-end applications. Here's what makes Vite stand out:

As a Development Server: Vite allows developers to work locally (on localhost). Its hot module replacement feature offers an excellent development experience. For example, when working on a React project, any changes you make are quickly reflected on your local page, while also keeping the current state intact.

Production Bundle: Behind the scenes, Vite uses Rollup for bundling. This results in highly optimized code ready for production environments.

Most of the popular frameworks in the front-end community now use Vite. This includes Astro, Nuxt, SvelteKit, Solid Start, and Qwik City. Essentially, apart from Next and Angular, Vite is the go-to choice for popular frameworks.

Why Use Vite? What Problems Does It Solve?

The core features of Vite are similar to those of Webpack, which is often used in the industry. So why choose Vite? What problems does it solve?

Vite fixes the "slow server start" issue

When you start a development server from scratch, traditional setups using a bundler have to process your entire app before anything can be served. This can be slow.

Vite changes the game by splitting your app's modules into two groups: dependencies and your own source code.

Dependencies are usually just regular JavaScript that doesn't change much while you're working. Some big dependencies, like those huge component libraries, can be a pain to handle. They come in different formats too, like ESM or CommonJS.

Here's where Vite shines. It uses esbuild, a tool written in Go, to quickly bundle these dependencies. We're talking 10 to 100 times faster than the usual JavaScript bundlers.

Your source code is a different story. It's got stuff that needs to be transformed, like JSX or CSS, and you'll be tweaking it a lot. Plus, you don't need to load all your code at once, especially when you're splitting it based on routes.

Vite serves your source code using native ESM. This means it lets the browser do some of the heavy lifting that a bundler usually would. Vite only steps in to transform and serve the code as and when the browser asks for it. If you've got code that's only used sometimes, Vite only processes it when it's actually needed.

Vite fixes the "slow server update" issue

In a typical development setup where a bundler is used, editing a file can slow things down. Why? Because rebuilding the entire bundle every time you make a change gets slower as your app gets bigger.

Some development servers try to be smart about it. They keep the bundle in memory, so when a file changes, they only update part of it. But, they still have to rebuild the whole thing and reload the page. This process can take a lot of time, and reloading the page means you lose whatever state the app was in. That's why some bundlers use Hot Module Replacement (HMR). It's a cool feature where a module can update itself on the fly without messing with the rest of the page. This is great for developer experience, but even HMR gets slower as your app grows.

Vite does HMR differently. It uses native ESM (a more modern way to handle modules). When you edit a file, Vite only updates the necessary parts – usually just the module you changed. This keeps things quick, no matter how large your app is.

Vite also uses smart HTTP headers to speed up even full page reloads. It does this by making the browser work more: if the source code hasn't changed, it doesn't bother the server (thanks to a 304 Not Modified status), and dependencies are cached so well they hardly ever need to ask the server again.

Vite helps optimize the production build

Here's the deal: Even though modern browsers can handle native ESM (a way to load JavaScript modules), using it straight-up in your final product is not the best idea. Why? Because every time your app needs another piece of code, it asks the server. And if your code has lots of imports, that's a lot of asking - which means a slower app.

To make sure your app loads quickly for users, you still need to bundle your code. That's where you combine files, remove unused code (tree-shaking), set up lazy-loading (loading code only when needed), and split common code into chunks (so users can cache them for faster reloads).

Getting your development server and your final, production-ready app to behave the same isn't easy. That's why Vite includes a special build command. This command automatically optimizes your app for production, handling all these complex tasks for you. So, you get a fast, efficient app without the headache.