- Brunch and Webpack are module bundlers. As such they have an opinion about the build process but by and large they are configured rather than scripted. In Webpack’s case things get a bit blurry because configurations are often assembled in a scripted manner.
- Gulp is a task runner and as such sees itself as taking the place of npm scripts. So to bundle modules it still has to use a bundler plugin such as Browserify which often can be done simply in npm itself. Gulp has more advanced facilities than npm scripts for coordinating build tasks - but from what I’ve seen it isn’t really configured as much as it is being scripted by writing Gulp tasks. One issue is that often in cases where Gulp seems simpler it really isn’t necessary (Why I Left Gulp and Grunt for npm Scripts (2016-Jan-17)).
Modern JavaScript for Dinosaurs gives an overview of using npm scripts and Webpack (see also How JavaScript bundlers work).
Aside: Here is an example where simple shell scripts are used to build a simple react application with browserify, babel-cli, watch, and uglify, cssshrink, jest-cli, babel-jest, react-addons-test-utils, eslint, eslint-plugin-react, eslint-plugin-babel, and flow-bin.
Now I don’t know whether that is the case here but I think often people try to choose a build tool before they fully understand the build process. I’m not saying that npm scripts are the be all and end all but they are likely the best way to get acquainted with the build process and as such can be pushed quite a ways. Once the build process is better understood and one’s needs are much clearer it should be easier to pick the right tool, be it webpack (SurviveJS - webpack), parcel, rollup.js or whatever.
