webpack/lib/errors/DuplicateModulesWarning.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports 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 Alexander Akait @alexander-akait
*/

"use strict";

const formatSize = require("../util/formatSize");
const WebpackError = require("./WebpackError");

/**
 * @typedef {object} DuplicateModuleDetails
 * @property {string} name
 * @property {number} chunks how many chunks carry a copy
 * @property {number} wasted bytes the extra copies cost
 */

class DuplicateModulesWarning extends WebpackError {
	/**
	 * Creates an instance of DuplicateModulesWarning.
	 * @param {DuplicateModuleDetails[]} modules the worst offenders, largest waste first
	 * @param {number} wasted bytes all duplicated copies cost together
	 */
	constructor(modules, wasted) {
		const list = modules
			.map(
				(module) =>
					`\n  ${module.name} (in ${module.chunks} chunks, ${formatSize(
						module.wasted
					)} extra)`
			)
			.join("");

		super(
			`duplicate modules: copies of the same module across chunks add ${formatSize(
				wasted
			)}:${list}\nA module reached from several chunks is emitted into each of them unless a shared chunk holds it. 'optimization.splitChunks' can pull it into one.\nFor more info visit https://webpack.js.org/plugins/split-chunks-plugin/`
		);

		/** @type {string} */
		this.name = "DuplicateModulesWarning";
	}
}

module.exports = DuplicateModulesWarning;