mirror of https://github.com/webpack/webpack.git
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README.md
This example demonstrates Scope Hoisting in combination with Code Splitting.
This is the dependency graph for the example: (solid lines express sync imports, dashed lines async imports)
All modules except cjs are EcmaScript modules. cjs is a CommonJs module.
The interesting thing here is that putting all modules in single scope won't work, because of multiple reasons:
- Modules
lazy,c,dandcjsneed to be in a separate chunk - Module
sharedis accessed by two chunks (different scopes) - Module
cjsis a CommonJs module
webpack therefore uses a approach called "Partial Scope Hoisting" or "Module concatenation", which chooses the largest possible subsets of ES modules which can be scope hoisted and combines them with the default webpack primitives.
While module concatenation identifiers in modules are renamed to avoid conflicts and internal imports are simplified. External imports and exports from the root module use the existing ESM constructs.
example.js
import { a, x, y } from "a";
import * as b from "b";
import("./lazy").then(function(lazy) {
console.log(a, b.a(), x, y, lazy.c, lazy.d.a, lazy.x, lazy.y);
});
lazy.js
export * from "c";
import * as d from "d";
export { d };
a.js
// module a
export var a = "a";
export * from "shared";
b.js
// module b
export function a() {
return "b";
};
c.js
// module c
import { c as e } from "cjs";
export var c = String.fromCharCode(e.charCodeAt(0) - 2);
export { x, y } from "shared";
d.js
// module d
export var a = "d";
cjs.js
// module cjs (commonjs)
exports.c = "e";
shared.js
// shared module
export var x = "x";
export * from "shared2";
shared2.js
// shared2 module
export var y = "y";
webpack.config.js
module.exports = {
// mode: "development" || "production",
optimization: {
usedExports: true,
concatenateModules: true,
chunkIds: "deterministic" // To keep filename consistent between different modes (for example building only)
}
};
dist/output.js
/******/ (() => { // webpackBootstrap
/******/ "use strict";
/******/ var __webpack_modules__ = ([
/* 0 */,
/* 1 */
/*!********************************************!*\
!*** ./node_modules/shared.js + 1 modules ***!
\********************************************/
/*! namespace exports */
/*! export x [provided] [used] [could be renamed] */
/*! export y [provided] [used] [could be renamed] */
/*! other exports [not provided] [unused] */
/*! runtime requirements: __webpack_exports__, __webpack_require__.d, __webpack_require__.* */
/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {
// EXPORTS
__webpack_require__.d(__webpack_exports__, {
"x": () => /* binding */ x,
"y": () => /* reexport */ y
});
// CONCATENATED MODULE: ./node_modules/shared2.js
// shared2 module
var y = "y";
// CONCATENATED MODULE: ./node_modules/shared.js
// shared module
var x = "x";
/***/ })
/******/ ]);
/* webpack runtime code */
/************************************************************************/
/******/ // The module cache
/******/ var __webpack_module_cache__ = {};
/******/
/******/ // The require function
/******/ function __webpack_require__(moduleId) {
/******/ // Check if module is in cache
/******/ if(__webpack_module_cache__[moduleId]) {
/******/ return __webpack_module_cache__[moduleId].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/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 + ".output.js";
/******/ };
/******/ })();
/******/
/******/ /* webpack/runtime/hasOwnProperty shorthand */
/******/ (() => {
/******/ __webpack_require__.o = (obj, prop) => Object.prototype.hasOwnProperty.call(obj, prop)
/******/ })();
/******/
/******/ /* 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 */
/******/ (() => {
/******/ __webpack_require__.p = "dist/";
/******/ })();
/******/
/******/ /* webpack/runtime/jsonp chunk loading */
/******/ (() => {
/******/ // object to store loaded and loading chunks
/******/ // undefined = chunk not loaded, null = chunk preloaded/prefetched
/******/ // Promise = chunk loading, 0 = chunk loaded
/******/ var installedChunks = {
/******/ 179: 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);
/******/ var loadingEnded = () => {
/******/ if(__webpack_require__.o(installedChunks, chunkId)) {
/******/ installedChunkData = installedChunks[chunkId];
/******/ if(installedChunkData !== 0) installedChunks[chunkId] = undefined;
/******/ if(installedChunkData) return installedChunkData[1];
/******/ }
/******/ };
/******/ var script = document.createElement('script');
/******/ var onScriptComplete;
/******/
/******/ script.charset = 'utf-8';
/******/ script.timeout = 120;
/******/ if (__webpack_require__.nc) {
/******/ script.setAttribute("nonce", __webpack_require__.nc);
/******/ }
/******/ script.src = url;
/******/
/******/ // create error before stack unwound to get useful stacktrace later
/******/ var error = new Error();
/******/ onScriptComplete = (event) => {
/******/ onScriptComplete = () => {
/******/
/******/ }
/******/ // avoid mem leaks in IE.
/******/ script.onerror = script.onload = null;
/******/ clearTimeout(timeout);
/******/ var reportError = loadingEnded();
/******/ if(reportError) {
/******/ 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;
/******/ reportError(error);
/******/ }
/******/ }
/******/ ;
/******/ var timeout = setTimeout(() => {
/******/ onScriptComplete({ type: 'timeout', target: script })
/******/ }, 120000);
/******/ script.onerror = script.onload = onScriptComplete;
/******/ document.head.appendChild(script);
/******/ } else installedChunks[chunkId] = 0;
/******/ }
/******/ }
/******/ };
/******/
/******/ // no prefetching
/******/
/******/ // no preloaded
/******/
/******/ // no HMR
/******/
/******/ // no HMR manifest
/******/
/******/ // no deferred startup
/******/
/******/ // install a JSONP callback for chunk loading
/******/ function webpackJsonpCallback(data) {
/******/ var chunkIds = data[0];
/******/ var moreModules = data[1];
/******/
/******/ var runtime = data[3];
/******/ // add "moreModules" to the modules object,
/******/ // then flag all "chunkIds" as loaded and fire callback
/******/ var moduleId, chunkId, i = 0, resolves = [];
/******/ for(;i < chunkIds.length; i++) {
/******/ chunkId = chunkIds[i];
/******/ if(__webpack_require__.o(installedChunks, chunkId) && installedChunks[chunkId]) {
/******/ resolves.push(installedChunks[chunkId][0]);
/******/ }
/******/ installedChunks[chunkId] = 0;
/******/ }
/******/ for(moduleId in moreModules) {
/******/ if(__webpack_require__.o(moreModules, moduleId)) {
/******/ __webpack_require__.m[moduleId] = moreModules[moduleId];
/******/ }
/******/ }
/******/ if(runtime) runtime(__webpack_require__);
/******/ if(parentJsonpFunction) parentJsonpFunction(data);
/******/ while(resolves.length) {
/******/ resolves.shift()();
/******/ }
/******/
/******/ };
/******/
/******/ var jsonpArray = window["webpackJsonp"] = window["webpackJsonp"] || [];
/******/ var oldJsonpFunction = jsonpArray.push.bind(jsonpArray);
/******/ jsonpArray.push = webpackJsonpCallback;
/******/ var parentJsonpFunction = oldJsonpFunction;
/******/ })();
/******/
/************************************************************************/
(() => {
/*!********************************!*\
!*** ./example.js + 2 modules ***!
\********************************/
/*! namespace exports */
/*! exports [not provided] [unused] */
/*! runtime requirements: __webpack_require__, __webpack_require__.e, __webpack_require__.* */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/shared.js (<- Module is referenced from different chunks by these modules: ./lazy.js + 2 modules) */
// EXTERNAL MODULE: ./node_modules/shared.js + 1 modules
var shared = __webpack_require__(1);
// CONCATENATED MODULE: ./node_modules/a.js
// module a
var a = "a";
// CONCATENATED MODULE: ./node_modules/b.js
// module b
function b_a() {
return "b";
};
// CONCATENATED MODULE: ./example.js
__webpack_require__.e(/*! import() */ 262).then(__webpack_require__.bind(__webpack_require__, /*! ./lazy */ 2)).then(function(lazy) {
console.log(a, b_a(), shared.x, shared.y, lazy.c, lazy.d.a, lazy.x, lazy.y);
});
})();
/******/ })()
;
dist/262.output.js
(window["webpackJsonp"] = window["webpackJsonp"] || []).push([[262],[
/* 0 */,
/* 1 */,
/* 2 */
/*!*****************************!*\
!*** ./lazy.js + 2 modules ***!
\*****************************/
/*! namespace exports */
/*! export c [provided] [maybe used (runtime-defined)] [usage prevents renaming] */
/*! export d [provided] [maybe used (runtime-defined)] [usage prevents renaming] */
/*! export a [provided] [maybe used (runtime-defined)] [usage prevents renaming] */
/*! other exports [not provided] [maybe used (runtime-defined)] */
/*! export x [provided] [maybe used (runtime-defined)] [usage prevents renaming] */
/*! export y [provided] [maybe used (runtime-defined)] [usage prevents renaming] */
/*! other exports [not provided] [maybe used (runtime-defined)] */
/*! runtime requirements: __webpack_require__.r, __webpack_exports__, __webpack_require__.d, __webpack_require__, __webpack_require__.* */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/cjs.js (<- Module is not an ECMAScript module) */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/shared.js (<- Module is referenced from different chunks by these modules: ./lazy.js + 2 modules) */
/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {
"use strict";
// ESM COMPAT FLAG
__webpack_require__.r(__webpack_exports__);
// EXPORTS
__webpack_require__.d(__webpack_exports__, {
"c": () => /* reexport */ c,
"x": () => /* reexport */ shared.x,
"y": () => /* reexport */ shared.y,
"d": () => /* reexport */ d_namespaceObject
});
// NAMESPACE OBJECT: ./node_modules/d.js
var d_namespaceObject = {};
__webpack_require__.r(d_namespaceObject);
__webpack_require__.d(d_namespaceObject, {
"a": () => a
});
// EXTERNAL MODULE: ./node_modules/cjs.js
var cjs = __webpack_require__(3);
// EXTERNAL MODULE: ./node_modules/shared.js + 1 modules
var shared = __webpack_require__(1);
// CONCATENATED MODULE: ./node_modules/c.js
// module c
var c = String.fromCharCode(cjs.c.charCodeAt(0) - 2);
// CONCATENATED MODULE: ./node_modules/d.js
// module d
var a = "d";
// CONCATENATED MODULE: ./lazy.js
/***/ }),
/* 3 */
/*!*****************************!*\
!*** ./node_modules/cjs.js ***!
\*****************************/
/*! default exports */
/*! export c [provided] [used] [could be renamed] */
/*! other exports [not provided] [unused] */
/*! runtime requirements: __webpack_exports__ */
/*! ModuleConcatenation bailout: Module is not an ECMAScript module */
/***/ ((__unused_webpack_module, exports) => {
// module cjs (commonjs)
exports.c = "e";
/***/ })
]]);
Minimized
(window.webpackJsonp=window.webpackJsonp||[]).push([[262],{262:(r,d,a)=>{"use strict";a.r(d),a.d(d,{c:()=>w,x:()=>e.x,y:()=>e.y,d:()=>c});var c={};a.r(c),a.d(c,{a:()=>n});var o=a(75),e=a(350),w=String.fromCharCode(o.c.charCodeAt(0)-2),n="d"},75:(r,d)=>{d.c="e"}}]);
Info
Unoptimized
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 5.0.0-beta.16
Asset Size
262.output.js 2.56 KiB [emitted]
output.js 10.1 KiB [emitted] [name: main]
Entrypoint main = output.js
chunk output.js (main) 372 bytes (javascript) 4.76 KiB (runtime) [entry] [rendered]
> ./example.js main
./example.js + 2 modules 272 bytes [built]
[no exports]
[no exports used]
entry ./example.js main
./node_modules/shared.js + 1 modules 100 bytes [built]
[exports: x, y]
[all exports used]
harmony side effect evaluation shared ./example.js + 2 modules ./node_modules/a.js 3:0-23
harmony export imported specifier shared ./example.js + 2 modules ./node_modules/a.js 3:0-23
harmony side effect evaluation shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
harmony export imported specifier shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
harmony export imported specifier shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
+ 7 hidden chunk modules
chunk 262.output.js 273 bytes [rendered]
> ./lazy ./example.js 4:0-16
./lazy.js + 2 modules 231 bytes [built]
[exports: c, d, x, y]
import() ./lazy ./example.js + 2 modules ./example.js 4:0-16
./node_modules/cjs.js 42 bytes [built]
[exports: c]
[all exports used]
harmony side effect evaluation cjs ./lazy.js + 2 modules ./node_modules/c.js 2:0-29
harmony import specifier cjs ./lazy.js + 2 modules ./node_modules/c.js 4:35-47
Production mode
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 5.0.0-beta.16
Asset Size
262.output.js 265 bytes [emitted]
output.js 1.7 KiB [emitted] [name: main]
Entrypoint main = output.js
chunk output.js (main) 372 bytes (javascript) 4.76 KiB (runtime) [entry] [rendered]
> ./example.js main
./example.js + 2 modules 272 bytes [built]
[no exports]
[no exports used]
entry ./example.js main
./node_modules/shared.js + 1 modules 100 bytes [built]
[exports: x, y]
[all exports used]
harmony side effect evaluation shared ./example.js + 2 modules ./node_modules/a.js 3:0-23
harmony export imported specifier shared ./example.js + 2 modules ./node_modules/a.js 3:0-23
harmony side effect evaluation shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
harmony export imported specifier shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
harmony export imported specifier shared ./lazy.js + 2 modules ./node_modules/c.js 6:0-30
+ 7 hidden chunk modules
chunk 262.output.js 273 bytes [rendered]
> ./lazy ./example.js 4:0-16
./lazy.js + 2 modules 231 bytes [built]
[exports: c, d, x, y]
import() ./lazy ./example.js + 2 modules ./example.js 4:0-16
./node_modules/cjs.js 42 bytes [built]
[exports: c]
[all exports used]
harmony side effect evaluation cjs ./lazy.js + 2 modules ./node_modules/c.js 2:0-29
harmony import specifier cjs ./lazy.js + 2 modules ./node_modules/c.js 4:35-47