package.lib.runtime.CreateFakeNamespaceObjectRuntimeModule.js Maven / Gradle / Ivy

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Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

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/*
	MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

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

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

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

	/**
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		const fn = RuntimeGlobals.createFakeNamespaceObject;
		return Template.asString([
			`var getProto = Object.getPrototypeOf ? ${runtimeTemplate.returningFunction(
				"Object.getPrototypeOf(obj)",
				"obj"
			)} : ${runtimeTemplate.returningFunction("obj.__proto__", "obj")};`,
			"var leafPrototypes;",
			"// create a fake namespace object",
			"// mode & 1: value is a module id, require it",
			"// mode & 2: merge all properties of value into the ns",
			"// mode & 4: return value when already ns object",
			"// mode & 16: return value when it's Promise-like",
			"// mode & 8|1: behave like require",
			// Note: must be a function (not arrow), because this is used in body!
			`${fn} = function(value, mode) {`,
			Template.indent([
				`if(mode & 1) value = this(value);`,
				`if(mode & 8) return value;`,
				"if(typeof value === 'object' && value) {",
				Template.indent([
					"if((mode & 4) && value.__esModule) return value;",
					"if((mode & 16) && typeof value.then === 'function') return value;"
				]),
				"}",
				"var ns = Object.create(null);",
				`${RuntimeGlobals.makeNamespaceObject}(ns);`,
				"var def = {};",
				"leafPrototypes = leafPrototypes || [null, getProto({}), getProto([]), getProto(getProto)];",
				"for(var current = mode & 2 && value; typeof current == 'object' && !~leafPrototypes.indexOf(current); current = getProto(current)) {",
				Template.indent([
					`Object.getOwnPropertyNames(current).forEach(${runtimeTemplate.expressionFunction(
						`def[key] = ${runtimeTemplate.returningFunction("value[key]", "")}`,
						"key"
					)});`
				]),
				"}",
				`def['default'] = ${runtimeTemplate.returningFunction("value", "")};`,
				`${RuntimeGlobals.definePropertyGetters}(ns, def);`,
				"return ns;"
			]),
			"};"
		]);
	}
}

module.exports = CreateFakeNamespaceObjectRuntimeModule;