webpack/lib/runtime/CreateFakeNamespaceObjectRuntimeModule.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
*/

"use strict";

const RuntimeGlobals = require("../RuntimeGlobals");
const Template = require("../Template");
const HelperRuntimeModule = require("./HelperRuntimeModule");

class CreateFakeNamespaceObjectRuntimeModule extends HelperRuntimeModule {
	constructor() {
		super("create fake namespace object");
	}

	/**
	 * @returns {string} runtime code
	 */
	generate() {
		const { runtimeTemplate } = this.compilation;
		const modern =
			runtimeTemplate.supportsArrowFunction() &&
			runtimeTemplate.supportsConst();
		const fn = RuntimeGlobals.createFakeNamespaceObject;
		return Template.asString([
			"// create a fake namespace object",
			"// mode & 1: value is a module id, require it",
			"// mode & 2: merge all properties of value into the ns",
			"// mode & 4: return value when already ns object",
			"// mode & 8|1: behave like require",
			// Note: must be a function (not arrow), because this is used in body!
			`${fn} = function(value, mode) {`,
			Template.indent([
				`if(mode & 1) value = this(value);`,
				`if(mode & 8) return value;`,
				"if((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;",
				"var ns = Object.create(null);",
				`${RuntimeGlobals.makeNamespaceObject}(ns);`,
				"var def = {};",
				"if(mode & 2 && typeof value == 'object' && value) {",
				Template.indent([
					modern
						? `for(const key in value) def[key] = () => value[key];`
						: `for(var key in value) def[key] = function(key) { return value[key]; }.bind(null, key);`
				]),
				"}",
				modern
					? "def['default'] = () => value;"
					: "def['default'] = function() { return value; };",
				`${RuntimeGlobals.definePropertyGetters}(ns, def);`,
				"return ns;"
			]),
			"};"
		]);
	}
}

module.exports = CreateFakeNamespaceObjectRuntimeModule;