Cleaning the Build

From the blog:
ajv - The Fastest JSON Schema Validator - Interview with Evgeny Poberezkin

Our current setup doesn't clean the build directory between builds. As a result, it will keep on accumulating files as our project changes. Given this can get annoying, we should clean it up in between.

This issue can be resolved either by using a webpack plugin or solving it outside of it. You could trigger rm -rf ./build && webpack or rimraf ./build && webpack in a npm script to keep it cross-platform. A task runner could work for this purpose as well.

I will show you how to solve this issue using webpack next.

Setting Up clean-webpack-plugin#

Install the clean-webpack-plugin first:

npm i clean-webpack-plugin --save-dev

Next, we need to define a little function to wrap the basic idea. We could use the plugin directly, but this feels like something that could be useful across projects, so it makes sense to push it to our library:

const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const PurifyCSSPlugin = require('purifycss-webpack-plugin');
const CleanWebpackPlugin = require('clean-webpack-plugin');
exports.clean = function(path) { return { plugins: [ new CleanWebpackPlugin([path]), ], }; };

Connect it with our project like this:



module.exports = function(env) {
  if (env === 'production') {
    return merge([
parts.loadJavaScript(, ... ]); } ... };

After this change, our build directory should remain nice and tidy while building. You can verify this by building the project and making sure no old files remained in the output directory.

Copying files is another common operation you can handle with a webpack plugin such as copy-webpack-plugin. It can be handy if you need to bring external files to your build without having webpack pointing at them directly. cpy-cli is a good option if you want to copy outside of webpack in a cross-platform way.


Often, you work with webpack like this: First, you identify a problem and then find a plugin to tackle it. It is entirely fine to solve these types of issues outside of webpack, but webpack can often handle them as well.

This book is available through Leanpub. By purchasing the book you support the development of further content. A part of profit (~30%) goes to Tobias Koppers, the author of Webpack.

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