How to use Webpack to combine JSON files from all subdirectories into one?

Question

Say I have a directory structured like this:

1. folder A
  1a. some_file.js
  1b. data.json
2. folder B
  2a. folder B1
     2a1. other_file.json
     2a2. data.json
  2b. folder B2
     2b1. data.json
3. output.json

Is there a webpack loader that can combine data.json in all subfolders, and output it to output.json?

I've found https://www.npmjs.com/package/json-files-merge-loader that seems to do something similar, but it seems to ask for each path to data.json, while I need something that goes through all folders and subfolders for data.json. All data.json keys are unique, and I want output.json to be one JSON object containing all key/value pair from all data.json.

Answer 1

webpack is not really suited for the use case you have. Many people think that webpack can be a replacement for a build system, but it's just a module bundler, it doesn't handle every task. Specifically:

1. webpack traverses require() and import statements, meaning it needs the modules to be statically defined. It's possible to get around this by writing a plugin or using a file generated from a template, but even if you did that...
2. webpack would have a hard time combining the JSON files in the way you want. webpack is good at bundling files into some sort of modules system (CommonJS or AMD). What you want is not a bundle containing modules, but a file containing arbitrary contents.

webpack might be able to do these things using some fancy plugins, but it's likely not worth it. In your case, you probably just want to write a Node script. If you want, you can use a plugin like this to run the code before build.

const fs = require('fs');
// https://github.com/isaacs/node-glob
const glob = require('glob');

const output = {};

glob('src/**/*.json', (error, files) => {
    files.forEach((filename) => {
        const contents = JSON.parse(fs.readFileSync(filename, 'utf8'));
        Object.assign(output, contents);
    });

    fs.writeFileSync('output.json', JSON.stringify(output));
});