wrapper-webpack-plugin/wrapper-webpack-plugin.js

Wraps output files (chunks) with custom text or code.

'use strict';

const ModuleFilenameHelpers = require("webpack/lib/ModuleFilenameHelpers");

class WrapperPlugin {

	/**
	 * @param {Object} args
	 * @param {string | Function} [args.header]  Text that will be prepended to an output file.
	 * @param {string | Function} [args.footer] Text that will be appended to an output file.
	 * @param {string | RegExp} [args.test] Tested against output file names to check if they should be affected by this
	 * plugin.
	 * @param {boolean} [args.afterOptimizations=false] Indicating whether this plugin should be activated before
	 * (`false`) or after (`true`) the optimization stage. Example use case: Set this to true if you want to avoid
	 * minification from affecting the text added by this plugin.
	 */
	constructor(args) {
		if (typeof args !== 'object') {
			throw new TypeError('Argument "args" must be an object.');
		}

		this.header = args.hasOwnProperty('header') ? args.header : '';
		this.footer = args.hasOwnProperty('footer') ? args.footer : '';
		this.afterOptimizations = args.hasOwnProperty('afterOptimizations') ? !!args.afterOptimizations : false;
		this.test = args.hasOwnProperty('test') ? args.test : '';
	}

	apply(compiler) {
		const ConcatSource = getSourceConcatenator(compiler);

		const header = this.header;
		const footer = this.footer;
		const tester = {test: this.test};

		compiler.hooks.compilation.tap('WrapperPlugin', (compilation) => {
			if (this.afterOptimizations) {
				compilation.hooks.afterOptimizeChunkAssets.tap('WrapperPlugin', (chunks) => {
					wrapChunks(compilation, chunks, footer, header);
				});
			} else {
				compilation.hooks.optimizeChunkAssets.tapAsync('WrapperPlugin', (chunks, done) => {
					wrapChunks(compilation, chunks, footer, header);
					done();
				});
			}
		});

		function wrapFile(compilation, fileName, chunkHash) {
			const headerContent = (typeof header === 'function') ? header(fileName, chunkHash) : header;
			const footerContent = (typeof footer === 'function') ? footer(fileName, chunkHash) : footer;

			compilation.assets[fileName] = new ConcatSource(
					String(headerContent),
					compilation.assets[fileName],
					String(footerContent),
			);
		}

		function wrapChunks(compilation, chunks) {
			for (const chunk of chunks) {
				const args = {
					hash: compilation.hash,
					chunkhash: chunk.hash,
				};
				for (const fileName of chunk.files) {
					if (ModuleFilenameHelpers.matchObject(tester, fileName)) {
						wrapFile(compilation, fileName, args);
					}
				}
			}
		} // wrapChunks
	}
}

module.exports = WrapperPlugin;

function getSourceConcatenator(compiler) {
	const webpack = compiler.webpack;
	if (webpack) {
		// webpack v5
		return webpack.sources.ConcatSource;
	}
	// webpack v4
	return require("webpack-sources").ConcatSource;
}