webpack 2 Documentation excerpts

Entry and Context

  • The entry object is where webpack looks to start building the bundle. The current directory is used by default.
  • The context is an absolute string to the directory that contains the entry files. At this point the application starts executing. If an array is passed all items will be executed.


The top-level output key contains set of options instructing webpack on how and where it should output your bundles, assets and anything else you bundle or load with webpack.

Only used when target is web, which uses JSONP for loading on-demand chunks, by adding script tags.


These options determine how the different types of modules within a project will be treated.


A Rule can be separated into three parts — Conditions, Results and nested Rules.

There are two input values for the conditions:

  • The resource: An absolute path to the file requested. It’s already resolved according the resolve rules.
  • The issuer: An absolute path to the file of the module which requested the resource. It’s the location of the import.

Example: When we import “./style.css” from app.js, the resource is /path/to/style.css and the issuer is /path/to/app.js.


These options change how modules are resolved.



externals configuration in webpack provides a way of not including a dependency in the bundle.

Module Resolution

A resolver is a library which helps in locating a module by its absolute path.


webpack enables use of loaders to preprocess files. This allows you to bundle any static resource way beyond JavaScript. You can easily write your own loaders using Node.js.

Comparison between webpack 2 & Rollup

webpack-2-vs-rollup - A demo


  • Well design with ES6’s new feature(bindings and cycles). Bundling the app or library using ES2015 and reducing bundling size with tree-shaking.
  • Configurations are more easily.

Rollup may be fading in trend and its designing long lasts. Still in developing with no stable version, and webpack 2 has been implementing its feature. The trend is going down in Github while webpack 2 going up.

Robin on Mar. 01, 2017

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written by 陈烨彬 Robin Chen , and published under (CC) BY-NC-SA.