webpack/lib/webpack.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 util = require("util");
const webpackOptionsSchemaCheck = require("../schemas/WebpackOptions.check.js");
const webpackOptionsSchema = require("../schemas/WebpackOptions.json");
const Compiler = require("./Compiler");
const MultiCompiler = require("./MultiCompiler");
const WebpackOptionsApply = require("./WebpackOptionsApply");
const {
	applyWebpackOptionsDefaults,
	applyWebpackOptionsBaseDefaults
} = require("./config/defaults");
const { getNormalizedWebpackOptions } = require("./config/normalization");
const NodeEnvironmentPlugin = require("./node/NodeEnvironmentPlugin");
const memoize = require("./util/memoize");

/** @typedef {import("../declarations/WebpackOptions").WebpackOptions} WebpackOptions */
/** @typedef {import("./Compiler").WatchOptions} WatchOptions */
/** @typedef {import("./MultiCompiler").MultiCompilerOptions} MultiCompilerOptions */
/** @typedef {import("./MultiStats")} MultiStats */
/** @typedef {import("./Stats")} Stats */

const getValidateSchema = memoize(() => require("./validateSchema"));

/**
 * @template T
 * @callback Callback
 * @param {Error=} err
 * @param {T=} stats
 * @returns {void}
 */

/**
 * @param {ReadonlyArray<WebpackOptions>} childOptions options array
 * @param {MultiCompilerOptions} options options
 * @returns {MultiCompiler} a multi-compiler
 */
const createMultiCompiler = (childOptions, options) => {
	const compilers = childOptions.map(options => createCompiler(options));
	const compiler = new MultiCompiler(compilers, options);
	for (const childCompiler of compilers) {
		if (childCompiler.options.dependencies) {
			compiler.setDependencies(
				childCompiler,
				childCompiler.options.dependencies
			);
		}
	}
	return compiler;
};

/**
 * @param {WebpackOptions} rawOptions options object
 * @returns {Compiler} a compiler
 */
const createCompiler = rawOptions => {
	const options = getNormalizedWebpackOptions(rawOptions);
	applyWebpackOptionsBaseDefaults(options);
	const compiler = new Compiler(options.context, options);
	new NodeEnvironmentPlugin({
		infrastructureLogging: options.infrastructureLogging
	}).apply(compiler);
	if (Array.isArray(options.plugins)) {
		for (const plugin of options.plugins) {
			if (typeof plugin === "function") {
				plugin.call(compiler, compiler);
			} else {
				plugin.apply(compiler);
			}
		}
	}
	applyWebpackOptionsDefaults(options);
	compiler.hooks.environment.call();
	compiler.hooks.afterEnvironment.call();
	new WebpackOptionsApply().process(options, compiler);
	compiler.hooks.initialize.call();
	return compiler;
};

/**
 * @callback WebpackFunctionSingle
 * @param {WebpackOptions} options options object
 * @param {Callback<Stats>=} callback callback
 * @returns {Compiler} the compiler object
 */

/**
 * @callback WebpackFunctionMulti
 * @param {ReadonlyArray<WebpackOptions> & MultiCompilerOptions} options options objects
 * @param {Callback<MultiStats>=} callback callback
 * @returns {MultiCompiler} the multi compiler object
 */

const webpack = /** @type {WebpackFunctionSingle & WebpackFunctionMulti} */ (
	/**
	 * @param {WebpackOptions | (ReadonlyArray<WebpackOptions> & MultiCompilerOptions)} options options
	 * @param {Callback<Stats> & Callback<MultiStats>=} callback callback
	 * @returns {Compiler | MultiCompiler}
	 */
	(options, callback) => {
		const create = () => {
			if (!webpackOptionsSchemaCheck(options)) {
				getValidateSchema()(webpackOptionsSchema, options);
			}
			/** @type {MultiCompiler|Compiler} */
			let compiler;
			let watch = false;
			/** @type {WatchOptions|WatchOptions[]} */
			let watchOptions;
			if (Array.isArray(options)) {
				/** @type {MultiCompiler} */
				compiler = createMultiCompiler(
					options,
					/** @type {MultiCompilerOptions} */ (options)
				);
				watch = options.some(options => options.watch);
				watchOptions = options.map(options => options.watchOptions || {});
			} else {
				const webpackOptions = /** @type {WebpackOptions} */ (options);
				/** @type {Compiler} */
				compiler = createCompiler(webpackOptions);
				watch = webpackOptions.watch;
				watchOptions = webpackOptions.watchOptions || {};
			}
			return { compiler, watch, watchOptions };
		};
		if (callback) {
			try {
				const { compiler, watch, watchOptions } = create();
				if (watch) {
					compiler.watch(watchOptions, callback);
				} else {
					compiler.run((err, stats) => {
						compiler.close(err2 => {
							callback(err || err2, stats);
						});
					});
				}
				return compiler;
			} catch (err) {
				process.nextTick(() => callback(err));
				return null;
			}
		} else {
			const { compiler, watch } = create();
			if (watch) {
				util.deprecate(
					() => {},
					"A 'callback' argument needs to be provided to the 'webpack(options, callback)' function when the 'watch' option is set. There is no way to handle the 'watch' option without a callback.",
					"DEP_WEBPACK_WATCH_WITHOUT_CALLBACK"
				)();
			}
			return compiler;
		}
	}
);

module.exports = webpack;