simple webpack bundle.js example

a.js

export default function() {
  console.log("hello aaa");
}

bundle.js

/******/ (() => { // webpackBootstrap
/******/ 	"use strict";
/******/ 	var __webpack_modules__ = ({

/***/ "./src/a.js":
/*!******************!*\
  !*** ./src/a.js ***!
  \******************/
/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {

__webpack_require__.r(__webpack_exports__);
/* harmony export */ __webpack_require__.d(__webpack_exports__, {
/* harmony export */   "default": () => (/* export default binding */ __WEBPACK_DEFAULT_EXPORT__)
/* harmony export */ });
/* harmony default export */ function __WEBPACK_DEFAULT_EXPORT__() {
  console.log("hello aaa");
}

/***/ }),

/***/ "./src/b.js":
/*!******************!*\
  !*** ./src/b.js ***!
  \******************/
/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {

__webpack_require__.r(__webpack_exports__);
/* harmony export */ __webpack_require__.d(__webpack_exports__, {
/* harmony export */   "default": () => (/* export default binding */ __WEBPACK_DEFAULT_EXPORT__)
/* harmony export */ });
/* harmony default export */ function __WEBPACK_DEFAULT_EXPORT__() {
  console.log("hello bbb");
}

/***/ }),

/***/ "./src/lib.js":
/*!********************!*\
  !*** ./src/lib.js ***!
  \********************/
/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {

__webpack_require__.r(__webpack_exports__);
/* harmony export */ __webpack_require__.d(__webpack_exports__, {
/* harmony export */   "a": () => (/* reexport safe */ _a__WEBPACK_IMPORTED_MODULE_0__.default),
/* harmony export */   "b": () => (/* reexport safe */ _b__WEBPACK_IMPORTED_MODULE_1__.default)
/* harmony export */ });
/* harmony import */ var _a__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! ./a */ "./src/a.js");
/* harmony import */ var _b__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(/*! ./b */ "./src/b.js");




/***/ })

/******/ 	});
/************************************************************************/
/******/ 	// The module cache
/******/ 	var __webpack_module_cache__ = {};
/******/ 	
/******/ 	// The require function
/******/ 	function __webpack_require__(moduleId) {
/******/ 		// Check if module is in cache
/******/ 		var cachedModule = __webpack_module_cache__[moduleId];
/******/ 		if (cachedModule !== undefined) {
/******/ 			return cachedModule.exports;
/******/ 		}
/******/ 		// Create a new module (and put it into the cache)
/******/ 		var module = __webpack_module_cache__[moduleId] = {
/******/ 			// no module.id needed
/******/ 			// no module.loaded needed
/******/ 			exports: {}
/******/ 		};
/******/ 	
/******/ 		// Execute the module function
/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
/******/ 	
/******/ 		// Return the exports of the module
/******/ 		return module.exports;
/******/ 	}
/******/ 	
/******/ 	// expose the modules object (__webpack_modules__)
/******/ 	__webpack_require__.m = __webpack_modules__;
/******/ 	
/************************************************************************/
/******/ 	/* webpack/runtime/create fake namespace object */
/******/ 	(() => {
/******/ 		var getProto = Object.getPrototypeOf ? (obj) => (Object.getPrototypeOf(obj)) : (obj) => (obj.__proto__);
/******/ 		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
/******/ 		__webpack_require__.t = function(value, mode) {
/******/ 			if(mode & 1) value = this(value);
/******/ 			if(mode & 8) return value;
/******/ 			if(typeof value === 'object' && value) {
/******/ 				if((mode & 4) && value.__esModule) return value;
/******/ 				if((mode & 16) && typeof value.then === 'function') return value;
/******/ 			}
/******/ 			var ns = Object.create(null);
/******/ 			__webpack_require__.r(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)) {
/******/ 				Object.getOwnPropertyNames(current).forEach((key) => (def[key] = () => (value[key])));
/******/ 			}
/******/ 			def['default'] = () => (value);
/******/ 			__webpack_require__.d(ns, def);
/******/ 			return ns;
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/define property getters */
/******/ 	(() => {
/******/ 		// define getter functions for harmony exports
/******/ 		__webpack_require__.d = (exports, definition) => {
/******/ 			for(var key in definition) {
/******/ 				if(__webpack_require__.o(definition, key) && !__webpack_require__.o(exports, key)) {
/******/ 					Object.defineProperty(exports, key, { enumerable: true, get: definition[key] });
/******/ 				}
/******/ 			}
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/ensure chunk */
/******/ 	(() => {
/******/ 		__webpack_require__.f = {};
/******/ 		// This file contains only the entry chunk.
/******/ 		// The chunk loading function for additional chunks
/******/ 		__webpack_require__.e = (chunkId) => {
/******/ 			return Promise.all(Object.keys(__webpack_require__.f).reduce((promises, key) => {
/******/ 				__webpack_require__.f[key](chunkId, promises);
/******/ 				return promises;
/******/ 			}, []));
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/get javascript chunk filename */
/******/ 	(() => {
/******/ 		// This function allow to reference async chunks
/******/ 		__webpack_require__.u = (chunkId) => {
/******/ 			// return url for filenames based on template
/******/ 			return "" + chunkId + ".bundle.js";
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/global */
/******/ 	(() => {
/******/ 		__webpack_require__.g = (function() {
/******/ 			if (typeof globalThis === 'object') return globalThis;
/******/ 			try {
/******/ 				return this || new Function('return this')();
/******/ 			} catch (e) {
/******/ 				if (typeof window === 'object') return window;
/******/ 			}
/******/ 		})();
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/hasOwnProperty shorthand */
/******/ 	(() => {
/******/ 		__webpack_require__.o = (obj, prop) => (Object.prototype.hasOwnProperty.call(obj, prop))
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/load script */
/******/ 	(() => {
/******/ 		var inProgress = {};
/******/ 		var dataWebpackPrefix = "tree-shaking:";
/******/ 		// loadScript function to load a script via script tag
/******/ 		__webpack_require__.l = (url, done, key, chunkId) => {
/******/ 			if(inProgress[url]) { inProgress[url].push(done); return; }
/******/ 			var script, needAttach;
/******/ 			if(key !== undefined) {
/******/ 				var scripts = document.getElementsByTagName("script");
/******/ 				for(var i = 0; i < scripts.length; i++) {
/******/ 					var s = scripts[i];
/******/ 					if(s.getAttribute("src") == url || s.getAttribute("data-webpack") == dataWebpackPrefix + key) { script = s; break; }
/******/ 				}
/******/ 			}
/******/ 			if(!script) {
/******/ 				needAttach = true;
/******/ 				script = document.createElement('script');
/******/ 		
/******/ 				script.charset = 'utf-8';
/******/ 				script.timeout = 120;
/******/ 				if (__webpack_require__.nc) {
/******/ 					script.setAttribute("nonce", __webpack_require__.nc);
/******/ 				}
/******/ 				script.setAttribute("data-webpack", dataWebpackPrefix + key);
/******/ 				script.src = url;
/******/ 			}
/******/ 			inProgress[url] = [done];
/******/ 			var onScriptComplete = (prev, event) => {
/******/ 				// avoid mem leaks in IE.
/******/ 				script.onerror = script.onload = null;
/******/ 				clearTimeout(timeout);
/******/ 				var doneFns = inProgress[url];
/******/ 				delete inProgress[url];
/******/ 				script.parentNode && script.parentNode.removeChild(script);
/******/ 				doneFns && doneFns.forEach((fn) => (fn(event)));
/******/ 				if(prev) return prev(event);
/******/ 			}
/******/ 			;
/******/ 			var timeout = setTimeout(onScriptComplete.bind(null, undefined, { type: 'timeout', target: script }), 120000);
/******/ 			script.onerror = onScriptComplete.bind(null, script.onerror);
/******/ 			script.onload = onScriptComplete.bind(null, script.onload);
/******/ 			needAttach && document.head.appendChild(script);
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/make namespace object */
/******/ 	(() => {
/******/ 		// define __esModule on exports
/******/ 		__webpack_require__.r = (exports) => {
/******/ 			if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
/******/ 				Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
/******/ 			}
/******/ 			Object.defineProperty(exports, '__esModule', { value: true });
/******/ 		};
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/publicPath */
/******/ 	(() => {
/******/ 		var scriptUrl;
/******/ 		if (__webpack_require__.g.importScripts) scriptUrl = __webpack_require__.g.location + "";
/******/ 		var document = __webpack_require__.g.document;
/******/ 		if (!scriptUrl && document) {
/******/ 			if (document.currentScript)
/******/ 				scriptUrl = document.currentScript.src
/******/ 			if (!scriptUrl) {
/******/ 				var scripts = document.getElementsByTagName("script");
/******/ 				if(scripts.length) scriptUrl = scripts[scripts.length - 1].src
/******/ 			}
/******/ 		}
/******/ 		// When supporting browsers where an automatic publicPath is not supported you must specify an output.publicPath manually via configuration
/******/ 		// or pass an empty string ("") and set the __webpack_public_path__ variable from your code to use your own logic.
/******/ 		if (!scriptUrl) throw new Error("Automatic publicPath is not supported in this browser");
/******/ 		scriptUrl = scriptUrl.replace(/#.*$/, "").replace(/\?.*$/, "").replace(/\/[^\/]+$/, "/");
/******/ 		__webpack_require__.p = scriptUrl;
/******/ 	})();
/******/ 	
/******/ 	/* webpack/runtime/jsonp chunk loading */
/******/ 	(() => {
/******/ 		// no baseURI
/******/ 		
/******/ 		// object to store loaded and loading chunks
/******/ 		// undefined = chunk not loaded, null = chunk preloaded/prefetched
/******/ 		// [resolve, reject, Promise] = chunk loading, 0 = chunk loaded
/******/ 		var installedChunks = {
/******/ 			"main": 0
/******/ 		};
/******/ 		
/******/ 		__webpack_require__.f.j = (chunkId, promises) => {
/******/ 				// JSONP chunk loading for javascript
/******/ 				var installedChunkData = __webpack_require__.o(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;
/******/ 				if(installedChunkData !== 0) { // 0 means "already installed".
/******/ 		
/******/ 					// a Promise means "currently loading".
/******/ 					if(installedChunkData) {
/******/ 						promises.push(installedChunkData[2]);
/******/ 					} else {
/******/ 						if(true) { // all chunks have JS
/******/ 							// setup Promise in chunk cache
/******/ 							var promise = new Promise((resolve, reject) => (installedChunkData = installedChunks[chunkId] = [resolve, reject]));
/******/ 							promises.push(installedChunkData[2] = promise);
/******/ 		
/******/ 							// start chunk loading
/******/ 							var url = __webpack_require__.p + __webpack_require__.u(chunkId);
/******/ 							// create error before stack unwound to get useful stacktrace later
/******/ 							var error = new Error();
/******/ 							var loadingEnded = (event) => {
/******/ 								if(__webpack_require__.o(installedChunks, chunkId)) {
/******/ 									installedChunkData = installedChunks[chunkId];
/******/ 									if(installedChunkData !== 0) installedChunks[chunkId] = undefined;
/******/ 									if(installedChunkData) {
/******/ 										var errorType = event && (event.type === 'load' ? 'missing' : event.type);
/******/ 										var realSrc = event && event.target && event.target.src;
/******/ 										error.message = 'Loading chunk ' + chunkId + ' failed.\n(' + errorType + ': ' + realSrc + ')';
/******/ 										error.name = 'ChunkLoadError';
/******/ 										error.type = errorType;
/******/ 										error.request = realSrc;
/******/ 										installedChunkData[1](error);
/******/ 									}
/******/ 								}
/******/ 							};
/******/ 							__webpack_require__.l(url, loadingEnded, "chunk-" + chunkId, chunkId);
/******/ 						} else installedChunks[chunkId] = 0;
/******/ 					}
/******/ 				}
/******/ 		};
/******/ 		
/******/ 		// no prefetching
/******/ 		
/******/ 		// no preloaded
/******/ 		
/******/ 		// no HMR
/******/ 		
/******/ 		// no HMR manifest
/******/ 		
/******/ 		// no on chunks loaded
/******/ 		
/******/ 		// install a JSONP callback for chunk loading
/******/ 		var webpackJsonpCallback = (parentChunkLoadingFunction, data) => {
/******/ 			var [chunkIds, moreModules, runtime] = data;
/******/ 			// add "moreModules" to the modules object,
/******/ 			// then flag all "chunkIds" as loaded and fire callback
/******/ 			var moduleId, chunkId, i = 0;
/******/ 			for(moduleId in moreModules) {
/******/ 				if(__webpack_require__.o(moreModules, moduleId)) {
/******/ 					__webpack_require__.m[moduleId] = moreModules[moduleId];
/******/ 				}
/******/ 			}
/******/ 			if(runtime) runtime(__webpack_require__);
/******/ 			if(parentChunkLoadingFunction) parentChunkLoadingFunction(data);
/******/ 			for(;i < chunkIds.length; i++) {
/******/ 				chunkId = chunkIds[i];
/******/ 				if(__webpack_require__.o(installedChunks, chunkId) && installedChunks[chunkId]) {
/******/ 					installedChunks[chunkId][0]();
/******/ 				}
/******/ 				installedChunks[chunkIds[i]] = 0;
/******/ 			}
/******/ 		
/******/ 		}
/******/ 		
/******/ 		var chunkLoadingGlobal = self["webpackChunktree_shaking"] = self["webpackChunktree_shaking"] || [];
/******/ 		chunkLoadingGlobal.forEach(webpackJsonpCallback.bind(null, 0));
/******/ 		chunkLoadingGlobal.push = webpackJsonpCallback.bind(null, chunkLoadingGlobal.push.bind(chunkLoadingGlobal));
/******/ 	})();
/******/ 	
/************************************************************************/
var __webpack_exports__ = {};
// This entry need to be wrapped in an IIFE because it need to be isolated against other modules in the chunk.
(() => {
/*!**********************!*\
  !*** ./src/index.js ***!
  \**********************/
__webpack_require__.r(__webpack_exports__);
/* harmony import */ var _lib__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! ./lib */ "./src/lib.js");

// import './index.css';
// import './other.css';

_lib__WEBPACK_IMPORTED_MODULE_0__.a.call(null);

window.b = () => {
  __webpack_require__.e(/*! import() */ "src_x_js").then(__webpack_require__.t.bind(__webpack_require__, /*! ./x.js */ "./src/x.js", 23)).then(lib => {
    console.log(lib);
    console.log(lib.hello())
  })
};

})();

/******/ })()
;

index.js

import { a } from './lib';

a.call(null);

window.b = () => {
  import('./x.js').then(lib => {
    console.log(lib);
    console.log(lib.hello())
  })
};

lib.js

export { default as a } from './a';

x.js

module.exports = {
  hello: () => 'hello'
}