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 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 validateSchema = require("./validateSchema");

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

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

/**
 * @param {WebpackOptions[]} childOptions options array
 * @returns {MultiCompiler} a multi-compiler
 */
const createMultiCompiler = childOptions => {
	const compilers = childOptions.map(options => createCompiler(options));
	const compiler = new MultiCompiler(compilers);
	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);
	compiler.options = 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 {WebpackOptions[]} options options objects
 * @param {Callback<MultiStats>=} callback callback
 * @returns {MultiCompiler} the multi compiler object
 */

const webpack = /** @type {WebpackFunctionSingle & WebpackFunctionMulti} */ ((
	options,
	callback
) => {
	const create = () => {
		validateSchema(webpackOptionsSchema, options);
		/** @type {MultiCompiler|Compiler} */
		let compiler;
		let watch = false;
		/** @type {WatchOptions|WatchOptions[]} */
		let watchOptions;
		if (Array.isArray(options)) {
			/** @type {MultiCompiler} */
			compiler = createMultiCompiler(options);
			watch = options.some(options => options.watch);
			watchOptions = options.map(options => options.watchOptions || {});
		} else {
			/** @type {Compiler} */
			compiler = createCompiler(options);
			watch = options.watch;
			watchOptions = options.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 need 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;