mirror of https://github.com/webpack/webpack.git
331 lines
11 KiB
Markdown
331 lines
11 KiB
Markdown
This example show how to use Code Splitting with the ES6 module syntax.
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The standard `import` is sync.
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`System.import(module: string) -> Promise` can be used to load modules on demand. This acts as split point for webpack and creates a chunk.
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Providing dynamic expressions to `System.import` is possible. The same limits as with dynamic expressions in `require` calls apply here. Each possible module creates an additional chunk. In this example `System.import("c/" + name)` creates two additional chunks (one for each file in `node_modules/c/`). This is called "async context".
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# example.js
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``` javascript
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import a from "a";
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System.import("b").then(function(b) {
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console.log("b loaded", b);
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})
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function loadC(name) {
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return System.import("c/" + name)
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}
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Promise.all([loadC("1"), loadC("2")]).then(function(arr) {
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console.log("c/1 and c/2 loaded", arr);
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});
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```
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# js/output.js
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<details><summary>`/******/ (function(modules) { /* webpackBootstrap */ })`</summary>
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``` javascript
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/******/ (function(modules) { // webpackBootstrap
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/******/ // install a JSONP callback for chunk loading
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/******/ var parentJsonpFunction = window["webpackJsonp"];
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/******/ window["webpackJsonp"] = function webpackJsonpCallback(chunkIds, moreModules, executeModules) {
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/******/ // add "moreModules" to the modules object,
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/******/ // then flag all "chunkIds" as loaded and fire callback
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/******/ var moduleId, chunkId, i = 0, resolves = [], result;
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/******/ for(;i < chunkIds.length; i++) {
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/******/ chunkId = chunkIds[i];
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/******/ if(installedChunks[chunkId])
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/******/ resolves.push(installedChunks[chunkId][0]);
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/******/ installedChunks[chunkId] = 0;
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/******/ }
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/******/ for(moduleId in moreModules) {
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/******/ if(Object.prototype.hasOwnProperty.call(moreModules, moduleId)) {
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/******/ modules[moduleId] = moreModules[moduleId];
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/******/ }
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/******/ }
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/******/ if(parentJsonpFunction) parentJsonpFunction(chunkIds, moreModules, executeModules);
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/******/ while(resolves.length)
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/******/ resolves.shift()();
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/******/ };
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/******/ // The module cache
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/******/ var installedModules = {};
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/******/ // objects to store loaded and loading chunks
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/******/ var installedChunks = {
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/******/ 3: 0
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/******/ };
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/******/ // The require function
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/******/ function __webpack_require__(moduleId) {
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/******/ // Check if module is in cache
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/******/ if(installedModules[moduleId])
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/******/ return installedModules[moduleId].exports;
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/******/ // Create a new module (and put it into the cache)
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/******/ var module = installedModules[moduleId] = {
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/******/ i: moduleId,
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/******/ l: false,
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/******/ exports: {}
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/******/ };
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/******/ // Execute the module function
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/******/ modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
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/******/ // Flag the module as loaded
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/******/ module.l = true;
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/******/ // Return the exports of the module
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/******/ return module.exports;
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/******/ }
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/******/ // This file contains only the entry chunk.
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/******/ // The chunk loading function for additional chunks
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/******/ __webpack_require__.e = function requireEnsure(chunkId) {
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/******/ if(installedChunks[chunkId] === 0)
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/******/ return Promise.resolve();
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/******/ // an Promise means "currently loading".
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/******/ if(installedChunks[chunkId]) {
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/******/ return installedChunks[chunkId][2];
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/******/ }
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/******/ // start chunk loading
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/******/ var head = document.getElementsByTagName('head')[0];
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/******/ var script = document.createElement('script');
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/******/ script.type = 'text/javascript';
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/******/ script.charset = 'utf-8';
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/******/ script.async = true;
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/******/ script.timeout = 120000;
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/******/ if (__webpack_require__.nc) {
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/******/ script.setAttribute("nonce", __webpack_require__.nc);
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/******/ }
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/******/ script.src = __webpack_require__.p + "" + chunkId + ".output.js";
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/******/ var timeout = setTimeout(onScriptComplete, 120000);
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/******/ script.onerror = script.onload = onScriptComplete;
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/******/ function onScriptComplete() {
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/******/ // avoid mem leaks in IE.
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/******/ script.onerror = script.onload = null;
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/******/ clearTimeout(timeout);
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/******/ var chunk = installedChunks[chunkId];
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/******/ if(chunk !== 0) {
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/******/ if(chunk) chunk[1](new Error('Loading chunk ' + chunkId + ' failed.'));
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/******/ installedChunks[chunkId] = undefined;
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/******/ }
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/******/ };
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/******/ var promise = new Promise(function(resolve, reject) {
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/******/ installedChunks[chunkId] = [resolve, reject];
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/******/ });
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/******/ installedChunks[chunkId][2] = promise;
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/******/ head.appendChild(script);
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/******/ return promise;
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/******/ };
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/******/ // expose the modules object (__webpack_modules__)
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/******/ __webpack_require__.m = modules;
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/******/ // expose the module cache
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/******/ __webpack_require__.c = installedModules;
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/******/ // identity function for calling harmony imports with the correct context
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/******/ __webpack_require__.i = function(value) { return value; };
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/******/ // define getter function for harmony exports
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/******/ __webpack_require__.d = function(exports, name, getter) {
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/******/ if(!__webpack_require__.o(exports, name)) {
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/******/ Object.defineProperty(exports, name, {
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/******/ configurable: false,
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/******/ enumerable: true,
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/******/ get: getter
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/******/ });
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/******/ }
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/******/ };
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/******/ // getDefaultExport function for compatibility with non-harmony modules
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/******/ __webpack_require__.n = function(module) {
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/******/ var getter = module && module.__esModule ?
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/******/ function getDefault() { return module['default']; } :
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/******/ function getModuleExports() { return module; };
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/******/ __webpack_require__.d(getter, 'a', getter);
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/******/ return getter;
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/******/ };
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/******/ // Object.prototype.hasOwnProperty.call
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/******/ __webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
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/******/ // __webpack_public_path__
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/******/ __webpack_require__.p = "js/";
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/******/ // on error function for async loading
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/******/ __webpack_require__.oe = function(err) { console.error(err); throw err; };
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/******/ // Load entry module and return exports
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/******/ return __webpack_require__(__webpack_require__.s = 5);
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/******/ })
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/************************************************************************/
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```
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</details>
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``` javascript
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/******/ ([
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/* 0 */
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/* unknown exports provided */
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/*!****************!*\
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!*** ./~/a.js ***!
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\****************/
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/***/ function(module, exports) {
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// module a
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/***/ },
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/* 1 */
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/* unknown exports provided */
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/* all exports used */
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/*!****************************!*\
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!*** ./~/c async ^\.\/.*$ ***!
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\****************************/
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/***/ function(module, exports, __webpack_require__) {
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var map = {
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"./1": [
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2,
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1
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],
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"./1.js": [
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2,
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1
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],
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"./2": [
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3,
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0
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],
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"./2.js": [
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3,
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0
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]
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};
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function webpackAsyncContext(req) {
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var ids = map[req]; if(!ids)
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return Promise.reject(new Error("Cannot find module '" + req + "'."));
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return __webpack_require__.e(ids[1]).then(function() {
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return __webpack_require__(ids[0]);
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});
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};
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webpackAsyncContext.keys = function webpackAsyncContextKeys() {
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return Object.keys(map);
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};
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module.exports = webpackAsyncContext;
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webpackAsyncContext.id = 1;
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/***/ },
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/* 2 */,
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/* 3 */,
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/* 4 */,
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/* 5 */
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/* unknown exports provided */
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/* all exports used */
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/*!********************!*\
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!*** ./example.js ***!
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\********************/
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/***/ function(module, exports, __webpack_require__) {
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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/* harmony import */ var __WEBPACK_IMPORTED_MODULE_0_a__ = __webpack_require__(/*! a */ 0);
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/* harmony import */ var __WEBPACK_IMPORTED_MODULE_0_a___default = __webpack_require__.n(__WEBPACK_IMPORTED_MODULE_0_a__);
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__webpack_require__.e/* import() */(2).then(__webpack_require__.bind(null, /*! b */ 4)).then(function(b) {
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console.log("b loaded", b);
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})
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function loadC(name) {
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return __webpack_require__(/*! c */ 1)("./" + name)
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}
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Promise.all([loadC("1"), loadC("2")]).then(function(arr) {
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console.log("c/1 and c/2 loaded", arr);
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});
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/***/ }
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/******/ ]);
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```
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# Info
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## Uncompressed
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```
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Hash: a7c705649f12226cfe93
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Version: webpack 2.2.0-rc.2
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Asset Size Chunks Chunk Names
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0.output.js 216 bytes 0 [emitted]
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1.output.js 216 bytes 1 [emitted]
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2.output.js 208 bytes 2 [emitted]
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output.js 7.22 kB 3 [emitted] main
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Entrypoint main = output.js
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chunk {0} 0.output.js 13 bytes {3} [rendered]
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[3] ./~/c/2.js 13 bytes {0} [optional] [built]
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context element ./2 [1] ./~/c async ^\.\/.*$
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context element ./2.js [1] ./~/c async ^\.\/.*$
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chunk {1} 1.output.js 13 bytes {3} [rendered]
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[2] ./~/c/1.js 13 bytes {1} [optional] [built]
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context element ./1 [1] ./~/c async ^\.\/.*$
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context element ./1.js [1] ./~/c async ^\.\/.*$
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chunk {2} 2.output.js 11 bytes {3} [rendered]
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> [5] ./example.js 3:0-18
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[4] ./~/b.js 11 bytes {2} [built]
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import() b [5] ./example.js 3:0-18
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chunk {3} output.js (main) 440 bytes [entry] [rendered]
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> main [5] ./example.js
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[0] ./~/a.js 11 bytes {3} [built]
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[no exports used]
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harmony import a [5] ./example.js 1:0-18
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[1] ./~/c async ^\.\/.*$ 160 bytes {3} [built]
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System.import context c [5] ./example.js 8:8-34
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[5] ./example.js 269 bytes {3} [built]
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```
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## Minimized (uglify-js, no zip)
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```
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Hash: a7c705649f12226cfe93
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Version: webpack 2.2.0-rc.2
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Asset Size Chunks Chunk Names
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0.output.js 38 bytes 0 [emitted]
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1.output.js 38 bytes 1 [emitted]
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2.output.js 38 bytes 2 [emitted]
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output.js 1.92 kB 3 [emitted] main
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Entrypoint main = output.js
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chunk {0} 0.output.js 13 bytes {3} [rendered]
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[3] ./~/c/2.js 13 bytes {0} [optional] [built]
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context element ./2 [1] ./~/c async ^\.\/.*$
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context element ./2.js [1] ./~/c async ^\.\/.*$
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chunk {1} 1.output.js 13 bytes {3} [rendered]
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[2] ./~/c/1.js 13 bytes {1} [optional] [built]
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context element ./1 [1] ./~/c async ^\.\/.*$
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context element ./1.js [1] ./~/c async ^\.\/.*$
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chunk {2} 2.output.js 11 bytes {3} [rendered]
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> [5] ./example.js 3:0-18
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[4] ./~/b.js 11 bytes {2} [built]
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import() b [5] ./example.js 3:0-18
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chunk {3} output.js (main) 440 bytes [entry] [rendered]
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> main [5] ./example.js
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[0] ./~/a.js 11 bytes {3} [built]
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[no exports used]
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harmony import a [5] ./example.js 1:0-18
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[1] ./~/c async ^\.\/.*$ 160 bytes {3} [built]
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System.import context c [5] ./example.js 8:8-34
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[5] ./example.js 269 bytes {3} [built]
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```
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