| Are you familiar with Java? If so, a web bundler is like a build tool which creates a single fat jar from all your source code and dependencies, so all you have to "deploy" is a single file... except the fat jar is just a (usually minified) js file (and sometimes other resources like a css output file that is the "bundled" version of multiple input CSS files, and other formats that "compile" to CSS, like SCSS [1] which used to be common because CSS lacked lots of features, like variables for example, but today is not as much needed). Without a bundler, when you write your application in multiple JS files that use npm dependencies (99.9% of web developers), how do you get the HTML to include links to everything? It's a bit tricky to do by hand, so you get a bundler to take one or more "entry points" and then anything that it refers to gets "bundled" together in a single output file that gets minified and "tree-shaken" (dead code elimination, i.e if you don't use some functions of a lib you imported, those functions are removed from the output). Bundlers also process the JS code to replace stuff like CommonJS module imports/exports with ESM (the now standard module system that browsers support) and may even translate usages of newer features to code that uses old, less convenient APIs (so that your code runs in older browsers). And of course, if you're writing code in Typescript (or another language that compiles down to JS) your bundler may automatically "compile" that to JS as well. I've been learning a lot about this because I am writing a project that is built on top of esbuild[2], a web bundler written in Go (I believe Vite uses it, and Vite is included in the benchmarks in this post). It's extremely fast, so fast I don't know why bother writing something in Rust to go even faster, I get all my code compiled in a few milliseconds with esbuild! Hope that helps. [1] https://sass-lang.com/documentation/syntax/ [2] https://esbuild.github.io/ |