webpack/lib/runtime/DefinePropertyGettersRuntimeModule.js

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.

/*
	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 DefinePropertyGettersRuntimeModule extends HelperRuntimeModule {
	constructor() {
		super("define property getters");
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		const fn = RuntimeGlobals.definePropertyGetters;
		return Template.asString([
			"// define getter/value functions for harmony exports",
			`${fn} = ${runtimeTemplate.basicFunction("exports, definition", [
				"if(Array.isArray(definition)) {",
				Template.indent([
					"var i = 0;",
					"while(i < definition.length) {",
					Template.indent([
						"var key = definition[i++];",
						"var binding = definition[i++];",
						`if(!${RuntimeGlobals.hasOwnProperty}(exports, key)) {`,
						Template.indent([
							"if(binding === 0) {",
							Template.indent([
								"Object.defineProperty(exports, key, { enumerable: true, value: definition[i++] });"
							]),
							"} else {",
							Template.indent([
								"Object.defineProperty(exports, key, { enumerable: true, get: binding });"
							]),
							"}"
						]),
						"} else if(binding === 0) { i++; }"
					]),
					"}"
				]),
				// TODO webpack 6: remove object format support. Internal code (e.g. ConcatenatedModule)
				// and third-party libraries may still call __webpack_require__.d() with an object.
				"} else {",
				Template.indent([
					"for(var key in definition) {",
					Template.indent([
						`if(${RuntimeGlobals.hasOwnProperty}(definition, key) && !${RuntimeGlobals.hasOwnProperty}(exports, key)) {`,
						Template.indent([
							"Object.defineProperty(exports, key, { enumerable: true, get: definition[key] });"
						]),
						"}"
					]),
					"}"
				]),
				"}"
			])};`
		]);
	}
}

module.exports = DefinePropertyGettersRuntimeModule;