WebPack Loader vs Plugin

Oct 30, 2023 · Kamesh Sethupathi

WebPack : Loader VS Plugin

Though there are couple of bundler available for javascript, Webpack steals the heart of most javascript developers.
The reason is obviously due to its vast ecosystem of loaders and plugins, which extend its core bundling functionality.
Even senior developers get confused between the purpose of loader and plugin. This article is for you if you dont want to be one of them.

WebPack at it’s core is just a module bundler.
When one file depends on another, webpack treats this as a dependency.
It starts the bundling process from the given entry files, scans for certain text within the content like import and evaluates them.
Finds the dependencies from the previous evaluation and add them to the dependency graph.
Does the same for the dependencies.
At last it generates one or more output bundles - often, only one.

Loaders work at the individual file level during or before the bundle is generated.
Out of the box, webpack only understands JavaScript and JSON files.
Loaders allow webpack to process other types of files and convert them into valid modules that can be consumed by your application and added to the dependency graph.

Plugins work at bundle or chunk level and usually work at the end of the bundle generation process. Plugins can also modify how the bundles themselves are created.
Plugins can deeply integrate into webpack because they can register hooks within webpacks build system and access (and modify) the compiler, and how it works, as well as the compilation.
Plugins have more powerful control than loaders.
Plugins can be leveraged to perform a wider range of tasks like bundle optimization, asset management and injection of environment variables.