This example show how to use Code Splitting with the ES6 module syntax.
The standard import is sync.
import(module: string) -> Promise can be used to load modules on demand. This acts as split point for webpack and creates a chunk.
Providing dynamic expressions to 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 import("c/" + name) creates two additional chunks (one for each file in node_modules/c/). This is called "async context".
import a from "a";
import("b").then(function(b) {
console.log("b loaded", b);
})
function loadC(name) {
return import("c/" + name);
}
Promise.all([loadC("1"), loadC("2")]).then(function(arr) {
console.log("c/1 and c/2 loaded", arr);
});/******/ (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(Object.prototype.hasOwnProperty.call(installedChunks, chunkId) && 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 = {
/******/ 2: 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);
/******/
/******/ // create error before stack unwound to get useful stacktrace later
/******/ var error = new Error();
/******/ 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;
/******/ error.message = 'Loading chunk ' + chunkId + ' failed.\n(' + errorType + ': ' + realSrc + ')';
/******/ error.name = 'ChunkLoadError';
/******/ 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 = 2);
/******/ })
/************************************************************************//******/ ([
/* 0 */,
/* 1 */,
/* 2 */
/*!********************!*\
!*** ./example.js ***!
\********************/
/*! no exports provided */
/***/ (function(module, __webpack_exports__, __webpack_require__) {
"use strict";
__webpack_require__.r(__webpack_exports__);
/* harmony import */ var a__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! a */ 3);
/* harmony import */ var a__WEBPACK_IMPORTED_MODULE_0___default = /*#__PURE__*/__webpack_require__.n(a__WEBPACK_IMPORTED_MODULE_0__);
__webpack_require__.e(/*! import() */ 3).then(__webpack_require__.t.bind(null, /*! b */ 5, 7)).then(function(b) {
console.log("b loaded", b);
})
function loadC(name) {
return __webpack_require__(4)("./" + name);
}
Promise.all([loadC("1"), loadC("2")]).then(function(arr) {
console.log("c/1 and c/2 loaded", arr);
});
/***/ }),
/* 3 */
/*!***************************!*\
!*** ./node_modules/a.js ***!
\***************************/
/*! no static exports found */
/***/ (function(module, exports) {
// module a
/***/ }),
/* 4 */
/*!*******************************************************!*\
!*** ./node_modules/c lazy ^\.\/.*$ namespace object ***!
\*******************************************************/
/*! no static exports found */
/***/ (function(module, exports, __webpack_require__) {
var map = {
"./1": [
0,
0
],
"./1.js": [
0,
0
],
"./2": [
1,
1
],
"./2.js": [
1,
1
]
};
function webpackAsyncContext(req) {
if(!__webpack_require__.o(map, req)) {
return Promise.resolve().then(function() {
var e = new Error("Cannot find module '" + req + "'");
e.code = 'MODULE_NOT_FOUND';
throw e;
});
}
var ids = map[req], id = ids[0];
return __webpack_require__.e(ids[1]).then(function() {
return __webpack_require__.t(id, 7);
});
}
webpackAsyncContext.keys = function webpackAsyncContextKeys() {
return Object.keys(map);
};
webpackAsyncContext.id = 4;
module.exports = webpackAsyncContext;
/***/ })
/******/ ]);Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 4.39.0
Asset Size Chunks Chunk Names
0.output.js 275 bytes 0 [emitted]
1.output.js 284 bytes 1 [emitted]
3.output.js 270 bytes 3 [emitted]
output.js 9.94 KiB 2 [emitted] main
Entrypoint main = output.js
chunk {0} 0.output.js 13 bytes <{2}> [rendered]
> ./1 [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./1
> ./1.js [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./1.js
1 module
chunk {1} 1.output.js 13 bytes <{2}> [rendered]
> ./2 [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./2
> ./2.js [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./2.js
1 module
chunk {2} output.js (main) 414 bytes >{0}< >{1}< >{3}< [entry] [rendered]
> ./example.js main
[2] ./example.js 243 bytes {2} [built]
[no exports]
single entry ./example.js main
[4] ./node_modules/c lazy ^\.\/.*$ namespace object 160 bytes {2} [built]
import() context lazy c [2] ./example.js 8:8-27
+ 1 hidden module
chunk {3} 3.output.js 11 bytes <{2}> [rendered]
> b [2] ./example.js 3:0-11
1 module
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 4.39.0
Asset Size Chunks Chunk Names
0.output.js 76 bytes 0 [emitted]
1.output.js 77 bytes 1 [emitted]
3.output.js 78 bytes 3 [emitted]
output.js 2.61 KiB 2 [emitted] main
Entrypoint main = output.js
chunk {0} 0.output.js 13 bytes <{2}> [rendered]
> ./1 [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./1
> ./1.js [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./1.js
1 module
chunk {1} 1.output.js 13 bytes <{2}> [rendered]
> ./2 [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./2
> ./2.js [4] ./node_modules/c lazy ^\.\/.*$ namespace object ./2.js
1 module
chunk {2} output.js (main) 414 bytes >{0}< >{1}< >{3}< [entry] [rendered]
> ./example.js main
[2] ./example.js 243 bytes {2} [built]
[no exports]
single entry ./example.js main
[4] ./node_modules/c lazy ^\.\/.*$ namespace object 160 bytes {2} [built]
import() context lazy c [2] ./example.js 8:8-27
+ 1 hidden module
chunk {3} 3.output.js 11 bytes <{2}> [rendered]
> b [2] ./example.js 3:0-11
1 module