webpack/lib/NamedModulesPlugin.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const createHash = require("./util/createHash");
const RequestShortener = require("./RequestShortener");

const getHash = str => {
	const hash = createHash("md4");
	hash.update(str);
	const digest = /** @type {string} */ (hash.digest("hex"));
	return digest.substr(0, 4);
};

class NamedModulesPlugin {
	constructor(options) {
		this.options = options || {};
	}

	apply(compiler) {
		compiler.hooks.compilation.tap("NamedModulesPlugin", compilation => {
			compilation.hooks.beforeModuleIds.tap("NamedModulesPlugin", modules => {
				const namedModules = new Map();
				const context = this.options.context || compiler.options.context;

				for (const module of modules) {
					if (module.id === null && module.libIdent) {
						module.id = module.libIdent({ context });
					}

					if (module.id !== null) {
						const namedModule = namedModules.get(module.id);
						if (namedModule !== undefined) {
							namedModule.push(module);
						} else {
							namedModules.set(module.id, [module]);
						}
					}
				}

				for (const namedModule of namedModules.values()) {
					if (namedModule.length > 1) {
						for (const module of namedModule) {
							const requestShortener = new RequestShortener(context);
							module.id = `${module.id}?${getHash(
								requestShortener.shorten(module.identifier())
							)}`;
						}
					}
				}
			});
		});
	}
}

module.exports = NamedModulesPlugin;