index.js

/*
 MIT License http://www.opensource.org/licenses/mit-license.php
 Based on the Webpack core BannerPLugin by Tobias Koppers @sokra
 and smart-banner-webpack-plugin by @johvin
 */

"use strict";

const ConcatSource = require("webpack-sources").ConcatSource;
const ModuleFilenameHelpers = require("webpack/lib/ModuleFilenameHelpers");

function wrapComment(str) {
	if(!str.includes("\n")) return `/*! ${str} */`;
	return `/*!\n * ${str.split("\n").join("\n * ")}\n */`;
}

class BannerPlugin {
	constructor(options) {
		if(arguments.length > 1)
			throw new Error("BannerPlugin only takes one argument (pass an options object)");
		if(typeof options === "string")
			options = {
				banner: options
			};
		this.options = options || {};
		this.banner = this.options.raw ? options.banner : wrapComment(options.banner);
	}

	apply(compiler) {
		let options = this.options;
		let banner = this.banner;

		compiler.plugin("compilation", (compilation) => {
			compilation.plugin("optimize-chunk-assets", (chunks, callback) => {
				chunks.forEach((chunk) => {
					if(options.entryOnly && !chunk.isInitial()) return;

					chunk.files
						.filter(ModuleFilenameHelpers.matchObject.bind(undefined, options))
						.forEach((file) =>
							compilation.assets[file] = new ConcatSource(
								banner.replace(/\[filename\]/g, file), "\n", compilation.assets[file]
							)
						);
				});
				callback();
			});
		});
	}
}

module.exports = BannerPlugin;