17 KiB
17 KiB
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,
occurrenceOrder: true // To keep filename consistent between different modes (for example building only)
}
};
dist/output.js
/******/ (function(modules) { /* webpackBootstrap */ })
/******/ (function(modules) { // webpackBootstrap
/******/ // install a JSONP callback for chunk loading
/******/ function webpackJsonpCallback(data) {
/******/ var chunkIds = data[0];
/******/ var moreModules = data[1];
/******/
/******/
/******/ // 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(installedChunks[chunkId]) {
/******/ resolves.push(installedChunks[chunkId][0]);
/******/ }
/******/ installedChunks[chunkId] = 0;
/******/ }
/******/ for(moduleId in moreModules) {
/******/ if(Object.prototype.hasOwnProperty.call(moreModules, moduleId)) {
/******/ modules[moduleId] = moreModules[moduleId];
/******/ }
/******/ }
/******/ if(parentJsonpFunction) parentJsonpFunction(data);
/******/
/******/ while(resolves.length) {
/******/ resolves.shift()();
/******/ }
/******/
/******/ };
/******/
/******/
/******/ // The module cache
/******/ var installedModules = {};
/******/
/******/ // object to store loaded and loading chunks
/******/ // undefined = chunk not loaded, null = chunk preloaded/prefetched
/******/ // Promise = chunk loading, 0 = chunk loaded
/******/ var installedChunks = {
/******/ 0: 0
/******/ };
/******/
/******/
/******/
/******/ // script path function
/******/ function jsonpScriptSrc(chunkId) {
/******/ return __webpack_require__.p + "" + chunkId + ".output.js"
/******/ }
/******/
/******/ // The require function
/******/ function __webpack_require__(moduleId) {
/******/
/******/ // Check if module is in cache
/******/ if(installedModules[moduleId]) {
/******/ return installedModules[moduleId].exports;
/******/ }
/******/ // Create a new module (and put it into the cache)
/******/ var module = installedModules[moduleId] = {
/******/ i: moduleId,
/******/ l: false,
/******/ exports: {}
/******/ };
/******/
/******/ // Execute the module function
/******/ modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
/******/
/******/ // Flag the module as loaded
/******/ module.l = true;
/******/
/******/ // Return the exports of the module
/******/ return module.exports;
/******/ }
/******/
/******/ // This file contains only the entry chunk.
/******/ // The chunk loading function for additional chunks
/******/ __webpack_require__.e = function requireEnsure(chunkId) {
/******/ var promises = [];
/******/
/******/
/******/ // JSONP chunk loading for javascript
/******/
/******/ var installedChunkData = installedChunks[chunkId];
/******/ if(installedChunkData !== 0) { // 0 means "already installed".
/******/
/******/ // a Promise means "currently loading".
/******/ if(installedChunkData) {
/******/ promises.push(installedChunkData[2]);
/******/ } else {
/******/ // setup Promise in chunk cache
/******/ var promise = new Promise(function(resolve, reject) {
/******/ installedChunkData = installedChunks[chunkId] = [resolve, reject];
/******/ });
/******/ promises.push(installedChunkData[2] = promise);
/******/
/******/ // start chunk loading
/******/ 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 = jsonpScriptSrc(chunkId);
/******/
/******/ onScriptComplete = function (event) {
/******/ // avoid mem leaks in IE.
/******/ script.onerror = script.onload = null;
/******/ clearTimeout(timeout);
/******/ var chunk = installedChunks[chunkId];
/******/ if(chunk !== 0) {
/******/ if(chunk) {
/******/ var errorType = event && (event.type === 'load' ? 'missing' : event.type);
/******/ var realSrc = event && event.target && event.target.src;
/******/ var error = new Error('Loading chunk ' + chunkId + ' failed.\n(' + errorType + ': ' + realSrc + ')');
/******/ error.type = errorType;
/******/ error.request = realSrc;
/******/ chunk[1](error);
/******/ }
/******/ installedChunks[chunkId] = undefined;
/******/ }
/******/ };
/******/ var timeout = setTimeout(function(){
/******/ onScriptComplete({ type: 'timeout', target: script });
/******/ }, 120000);
/******/ script.onerror = script.onload = onScriptComplete;
/******/ document.head.appendChild(script);
/******/ }
/******/ }
/******/ return Promise.all(promises);
/******/ };
/******/
/******/ // expose the modules object (__webpack_modules__)
/******/ __webpack_require__.m = modules;
/******/
/******/ // expose the module cache
/******/ __webpack_require__.c = installedModules;
/******/
/******/ // define getter function for harmony exports
/******/ __webpack_require__.d = function(exports, name, getter) {
/******/ if(!__webpack_require__.o(exports, name)) {
/******/ Object.defineProperty(exports, name, { enumerable: true, get: getter });
/******/ }
/******/ };
/******/
/******/ // define __esModule on exports
/******/ __webpack_require__.r = function(exports) {
/******/ if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
/******/ Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
/******/ }
/******/ Object.defineProperty(exports, '__esModule', { value: true });
/******/ };
/******/
/******/ // 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
/******/ __webpack_require__.t = function(value, mode) {
/******/ if(mode & 1) value = __webpack_require__(value);
/******/ if(mode & 8) return value;
/******/ if((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;
/******/ var ns = Object.create(null);
/******/ __webpack_require__.r(ns);
/******/ Object.defineProperty(ns, 'default', { enumerable: true, value: value });
/******/ if(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));
/******/ return ns;
/******/ };
/******/
/******/ // getDefaultExport function for compatibility with non-harmony modules
/******/ __webpack_require__.n = function(module) {
/******/ var getter = module && module.__esModule ?
/******/ function getDefault() { return module['default']; } :
/******/ function getModuleExports() { return module; };
/******/ __webpack_require__.d(getter, 'a', getter);
/******/ return getter;
/******/ };
/******/
/******/ // Object.prototype.hasOwnProperty.call
/******/ __webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
/******/
/******/ // __webpack_public_path__
/******/ __webpack_require__.p = "dist/";
/******/
/******/ // on error function for async loading
/******/ __webpack_require__.oe = function(err) { console.error(err); throw err; };
/******/
/******/ var jsonpArray = window["webpackJsonp"] = window["webpackJsonp"] || [];
/******/ var oldJsonpFunction = jsonpArray.push.bind(jsonpArray);
/******/ jsonpArray.push = webpackJsonpCallback;
/******/ jsonpArray = jsonpArray.slice();
/******/ for(var i = 0; i < jsonpArray.length; i++) webpackJsonpCallback(jsonpArray[i]);
/******/ var parentJsonpFunction = oldJsonpFunction;
/******/
/******/
/******/ // Load entry module and return exports
/******/ return __webpack_require__(__webpack_require__.s = 1);
/******/ })
/************************************************************************/
/******/ ([
/* 0 */
/*!********************************************!*\
!*** ./node_modules/shared.js + 1 modules ***!
\********************************************/
/*! exports provided: x, y */
/*! exports used: x, y */
/***/ (function(module, __webpack_exports__, __webpack_require__) {
"use strict";
// CONCATENATED MODULE: ./node_modules/shared2.js
// shared2 module
var y = "y";
// CONCATENATED MODULE: ./node_modules/shared.js
/* harmony export (binding) */ __webpack_require__.d(__webpack_exports__, "a", function() { return x; });
/* concated harmony reexport y */__webpack_require__.d(__webpack_exports__, "b", function() { return y; });
// shared module
var x = "x";
/***/ }),
/* 1 */
/*!********************************!*\
!*** ./example.js + 2 modules ***!
\********************************/
/*! no exports provided */
/*! all exports used */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/shared.js because of ./node_modules/c.js */
/***/ (function(module, __webpack_exports__, __webpack_require__) {
"use strict";
__webpack_require__.r(__webpack_exports__);
// EXTERNAL MODULE: ./node_modules/shared.js + 1 modules
var shared = __webpack_require__(0);
// 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() */ 1).then(__webpack_require__.bind(null, /*! ./lazy */ 3)).then(function(lazy) {
console.log(a, b_a(), shared["a" /* x */], shared["b" /* y */], lazy.c, lazy.d.a, lazy.x, lazy.y);
});
/***/ })
/******/ ]);
dist/1.output.js
(window["webpackJsonp"] = window["webpackJsonp"] || []).push([[1],[
/* 0 */,
/* 1 */,
/* 2 */
/*!*****************************!*\
!*** ./node_modules/cjs.js ***!
\*****************************/
/*! no static exports found */
/*! exports used: c */
/*! ModuleConcatenation bailout: Module is not an ECMAScript module */
/***/ (function(module, exports) {
// module cjs (commonjs)
exports.c = "e";
/***/ }),
/* 3 */
/*!*****************************!*\
!*** ./lazy.js + 2 modules ***!
\*****************************/
/*! exports provided: d, c, x, y */
/*! all exports used */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/cjs.js (<- Module is not an ECMAScript module) */
/*! ModuleConcatenation bailout: Cannot concat with ./node_modules/shared.js */
/***/ (function(module, __webpack_exports__, __webpack_require__) {
"use strict";
__webpack_require__.r(__webpack_exports__);
var d_namespaceObject = {};
__webpack_require__.r(d_namespaceObject);
__webpack_require__.d(d_namespaceObject, "a", function() { return a; });
// EXTERNAL MODULE: ./node_modules/cjs.js
var cjs = __webpack_require__(2);
// EXTERNAL MODULE: ./node_modules/shared.js + 1 modules
var shared = __webpack_require__(0);
// 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
/* concated harmony reexport c */__webpack_require__.d(__webpack_exports__, "c", function() { return c; });
/* concated harmony reexport x */__webpack_require__.d(__webpack_exports__, "x", function() { return shared["a" /* x */]; });
/* concated harmony reexport y */__webpack_require__.d(__webpack_exports__, "y", function() { return shared["b" /* y */]; });
/* concated harmony reexport d */__webpack_require__.d(__webpack_exports__, "d", function() { return d_namespaceObject; });
/***/ })
]]);
Minimized
(window.webpackJsonp=window.webpackJsonp||[]).push([[1],[,,function(n,r){r.c="e"},function(n,r,t){"use strict";t.r(r);var c={};t.r(c),t.d(c,"a",function(){return e});var o=t(2),u=t(0),d=String.fromCharCode(o.c.charCodeAt(0)-2),e="d";t.d(r,"c",function(){return d}),t.d(r,"x",function(){return u.a}),t.d(r,"y",function(){return u.b}),t.d(r,"d",function(){return c})}]]);
Info
Unoptimized
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 4.29.6
Asset Size Chunks Chunk Names
1.output.js 1.9 KiB 1 [emitted]
output.js 9.41 KiB 0 [emitted] main
Entrypoint main = output.js
chunk {0} output.js (main) 372 bytes >{1}< [entry] [rendered]
> ./example.js main
[0] ./node_modules/shared.js + 1 modules 100 bytes {0} [built]
[exports: x, y]
[all exports used]
harmony side effect evaluation shared [1] ./example.js + 2 modules 3:0-23
harmony export imported specifier shared [1] ./example.js + 2 modules 3:0-23
harmony side effect evaluation shared [3] ./lazy.js + 2 modules 6:0-30
harmony export imported specifier shared [3] ./lazy.js + 2 modules 6:0-30
harmony export imported specifier shared [3] ./lazy.js + 2 modules 6:0-30
| 2 modules
[1] ./example.js + 2 modules 272 bytes {0} [built]
[no exports]
single entry ./example.js main
| ./example.js 161 bytes [built]
| [no exports]
| single entry ./example.js main
| + 2 hidden modules
chunk {1} 1.output.js 273 bytes <{0}> [rendered]
> ./lazy [] 4:0-16
[3] ./lazy.js + 2 modules 231 bytes {1} [built]
[exports: d, c, x, y]
import() ./lazy ./example.js 4:0-16
| ./lazy.js 57 bytes [built]
| [exports: d, c, x, y]
| import() ./lazy ./example.js 4:0-16
| + 2 hidden modules
+ 1 hidden module
Production mode
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 4.29.6
Asset Size Chunks Chunk Names
1.output.js 369 bytes 1 [emitted]
output.js 2.17 KiB 0 [emitted] main
Entrypoint main = output.js
chunk {0} output.js (main) 372 bytes >{1}< [entry] [rendered]
> ./example.js main
[0] ./node_modules/shared.js + 1 modules 100 bytes {0} [built]
[exports: x, y]
[all exports used]
harmony side effect evaluation shared [1] ./example.js + 2 modules 3:0-23
harmony export imported specifier shared [1] ./example.js + 2 modules 3:0-23
harmony side effect evaluation shared [3] ./lazy.js + 2 modules 6:0-30
harmony export imported specifier shared [3] ./lazy.js + 2 modules 6:0-30
harmony export imported specifier shared [3] ./lazy.js + 2 modules 6:0-30
| 2 modules
[1] ./example.js + 2 modules 272 bytes {0} [built]
[no exports]
single entry ./example.js main
| ./example.js 161 bytes [built]
| [no exports]
| single entry ./example.js main
| + 2 hidden modules
chunk {1} 1.output.js 273 bytes <{0}> [rendered]
> ./lazy [] 4:0-16
[3] ./lazy.js + 2 modules 231 bytes {1} [built]
[exports: d, c, x, y]
import() ./lazy ./example.js 4:0-16
| ./lazy.js 57 bytes [built]
| [exports: d, c, x, y]
| import() ./lazy ./example.js 4:0-16
| + 2 hidden modules
+ 1 hidden module