hash-dictionary-plugin.js

const defaults = {
	filename: 'versions.json',
};

class HashDictionaryPlugin {
	constructor(options) {
		this.options = Object.assign({}, defaults, options);
	}

	apply(compiler) {
		compiler.plugin('emit', (compilation, done) => {
			const {
				context,
				outputPath,
			} = compilation.compiler;

			const stats = compilation
				.getStats()
				.toJson({
					source: false,
					modules: false,
					publicPath: true,
				});

			const files = stats.chunks
				.reduce((result, chunk) => {
					const {hash} = chunk;
					const files = chunk.files.map(basename => {
						const filepath = path.join(outputPath, basename);

						return {
							hash,
							basename,
							cwd: context,
							path: filepath,
							dirname: outputPath,
							relative: path.relative(context, filepath),
						};
					});

					return result.concat(files);
				}, [])
				.reduce((result, record) => {
					result[record.relative] = record;
					return result;
				}, {});

			const contents = JSON.stringify(files);

			compilation.assets[this.options.filename] = {
				source() {
					return contents;
				},

				size() {
					return contents.length;
				},
			};

			done();
		});
	}
};