Why to use webpack-node-externals in node?

Question

I'm using webpack to bundle my typescript nodejs code.

I use webpack-node-externals to avoid errors in node_modules during the compile time.

webpack-node-externals says that, allows you to define externals - modules that should not be bundled.

But why? Webpack should bundle everything that I need to start my bundle right? It can extract and remove module that I don't use. (tree-shake for example).

If I use webpack-node-externals, then I'll have to do npm i in my prod folder to get all the dependencies.

I think this is miss the point of webpack can do. right?

then I'll have to do npm i in my prod folder to get all the dependencies. - this is what you likely should do any way. Webpack cannot bundle Node native modules, while they are common. It seems that you're misunderstanding the role of Webpack in Node app. There's a chance that you don't need it there at all. — Estus Flask
webpack cannot bundle fs, path, some things like that, and also some modules you installed that are binary modules. — PlayMa256

Jeffrey Sweeney Jeffrey Sweeney · Accepted Answer · 2019-06-10T21:32:03

I think you are correct that in your case, bundling into a single file would make more sense. webpack-node-external appears to be designed for use of NodeJS libraries, not standalone apps. From their doc:

When writing a node library, for instance, you may want to split your code to several files, and use Webpack to bundle them. However - you wouldn't want to bundle your code with its entire node_modules dependencies, for two reasons:

It will bloat your library on npm.

It goes against the entire npm dependencies management. If you're using Lodash, and the consumer of your library also has the same Lodash dependency, npm makes sure that it will be added only once. But bundling Lodash in your library will actually make it included twice, since npm is no longer managing this dependency.

As a consumer of a library, I want the library code to include only its logic, and just state its dependencies so they could me merged/resolved with the rest of the dependencies in my project. Bundling your code with your dependencies makes it virtually impossible.

I disagree with the comments that suggest Webpack was not designed to bundle Node scripts, considering that Webpack has a specific setting for just that (target). Unfortunately, there are too many third-party libraries that do not play nice with Webpack (as I just discovered today), so pragmatically speaking you're better off installing modules in the distribution folder anyway.

Why to use webpack-node-externals in node?

2 Answers