webpack/lib/SetVarMainTemplatePlugin.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 { ConcatSource } = require("webpack-sources");

/** @typedef {import("./Compilation")} Compilation */

class SetVarMainTemplatePlugin {
	/**
	 * @param {string} varExpression the accessor where the library is exported
	 * @param {boolean} copyObject specify copying the exports
	 */
	constructor(varExpression, copyObject) {
		/** @type {string} */
		this.varExpression = varExpression;
		/** @type {boolean} */
		this.copyObject = copyObject;
	}

	/**
	 * @param {Compilation} compilation the compilation instance
	 * @returns {void}
	 */
	apply(compilation) {
		const { mainTemplate, chunkTemplate } = compilation;

		const onRenderWithEntry = (source, chunk, hash) => {
			const varExpression = mainTemplate.getAssetPath(this.varExpression, {
				hash,
				chunk
			});
			if (this.copyObject) {
				return new ConcatSource(
					`(function(e, a) { for(var i in a) e[i] = a[i]; }(${varExpression}, `,
					source,
					"))"
				);
			} else {
				const prefix = `${varExpression} =\n`;
				return new ConcatSource(prefix, source);
			}
		};

		for (const template of [mainTemplate, chunkTemplate]) {
			template.hooks.renderWithEntry.tap(
				"SetVarMainTemplatePlugin",
				onRenderWithEntry
			);
		}

		mainTemplate.hooks.globalHashPaths.tap(
			"SetVarMainTemplatePlugin",
			paths => {
				if (this.varExpression) paths.push(this.varExpression);
				return paths;
			}
		);
		mainTemplate.hooks.hash.tap("SetVarMainTemplatePlugin", hash => {
			hash.update("set var");
			hash.update(`${this.varExpression}`);
			hash.update(`${this.copyObject}`);
		});
	}
}

module.exports = SetVarMainTemplatePlugin;