webpack/examples/multi-part-library/README.md

This example demonstrates how to build a complex library with webpack. The library consist of multiple parts that are usable on its own and together.

When using this library with script tags it exports itself to the namespace `MyLibrary` and each part to a property in this namespace (`MyLibrary.alpha` and `MyLibrary.beta`). When consuming the library with CommonsJs or AMD it just export each part.

We are using multiple entry points (`entry` option) to build every part of the library as separate output file. The `output.filename` option contains `[name]` to give each output file a different name.

We are using the `libraryTarget` option to generate a UMD ([Universal Module Definition](https://github.com/umdjs/umd)) module that is consumable in CommonsJs, AMD and with script tags. The `library` option defines the namespace. We are using `[name]` in the `library` option to give every entry a different namespace.

You can see that webpack automatically wraps your module so that it is consumable in every environment. All you need is this simple config.

Note: You can also use the `library` and `libraryTarget` options without multiple entry points. Then you don't need `[name]`.

Note: When your library has dependencies that should not be included in the compiled version, you can use the `externals` option. See [externals example](https://github.com/webpack/webpack/tree/master/examples/externals).

# webpack.config.js

```javascript
var path = require("path");
module.exports = {
	// mode: "development || "production",
	entry: {
		alpha: "./alpha",
		beta: "./beta"
	},
	output: {
		path: path.join(__dirname, "dist"),
		filename: "MyLibrary.[name].js",
		library: ["MyLibrary", "[name]"],
		libraryTarget: "umd"
	}
};
```

# dist/MyLibrary.alpha.js

```javascript
(function webpackUniversalModuleDefinition(root, factory) {
	if(typeof exports === 'object' && typeof module === 'object')
		module.exports = factory();
	else if(typeof define === 'function' && define.amd)
		define([], factory);
	else if(typeof exports === 'object')
		exports["alpha"] = factory();
	else
		root["MyLibrary"] = root["MyLibrary"] || {}, root["MyLibrary"]["alpha"] = factory();
})(window, function() {
return /******/ (() => { // webpackBootstrap
/******/ 	var __webpack_modules__ = ([
/* 0 */
/*!******************!*\
  !*** ./alpha.js ***!
  \******************/
/*! exports [maybe provided (runtime-defined)] [maybe used (runtime-defined)] */
/*! runtime requirements: module */
/***/ ((module) => {

module.exports = "alpha";

/***/ })
/******/ 	]);
```

<details><summary><code>/* webpack runtime code */</code></summary>

``` js
/************************************************************************/
/******/ 	// 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] = {
/******/ 			i: moduleId,
/******/ 			l: false,
/******/ 			exports: {}
/******/ 		};
/******/ 	
/******/ 		// Execute the module function
/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
/******/ 	
/******/ 		// Flag the module as loaded
/******/ 		module.l = true;
/******/ 	
/******/ 		// Return the exports of the module
/******/ 		return module.exports;
/******/ 	}
/******/ 	
/************************************************************************/
```

</details>

``` js
/******/ 	// module exports must be returned from runtime so entry inlining is disabled
/******/ 	// startup
/******/ 	// Load entry module and return exports
/******/ 	return __webpack_require__(0);
/******/ })()
;
});
```

# dist/MyLibrary.beta.js

```javascript
(function webpackUniversalModuleDefinition(root, factory) {
	if(typeof exports === 'object' && typeof module === 'object')
		module.exports = factory();
	else if(typeof define === 'function' && define.amd)
		define([], factory);
	else if(typeof exports === 'object')
		exports["beta"] = factory();
	else
		root["MyLibrary"] = root["MyLibrary"] || {}, root["MyLibrary"]["beta"] = factory();
})(window, function() {
return /******/ (() => { // webpackBootstrap
/******/ 	var __webpack_modules__ = ([
/* 0 */,
/* 1 */
/*!*****************!*\
  !*** ./beta.js ***!
  \*****************/
/*! exports [maybe provided (runtime-defined)] [maybe used (runtime-defined)] */
/*! runtime requirements: module */
/***/ ((module) => {

module.exports = "beta";

/***/ })
/******/ 	]);
```

<details><summary><code>/* webpack runtime code */</code></summary>

``` js
/************************************************************************/
/******/ 	// 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] = {
/******/ 			i: moduleId,
/******/ 			l: false,
/******/ 			exports: {}
/******/ 		};
/******/ 	
/******/ 		// Execute the module function
/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
/******/ 	
/******/ 		// Flag the module as loaded
/******/ 		module.l = true;
/******/ 	
/******/ 		// Return the exports of the module
/******/ 		return module.exports;
/******/ 	}
/******/ 	
/************************************************************************/
```

</details>

``` js
/******/ 	// module exports must be returned from runtime so entry inlining is disabled
/******/ 	// startup
/******/ 	// Load entry module and return exports
/******/ 	return __webpack_require__(1);
/******/ })()
;
});
```

# Info

## Unoptimized

```
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 5.0.0-beta.6
             Asset      Size
MyLibrary.alpha.js  1.97 KiB  [emitted]  [name: alpha]
 MyLibrary.beta.js  1.98 KiB  [emitted]  [name: beta]
Entrypoint alpha = MyLibrary.alpha.js
Entrypoint beta = MyLibrary.beta.js
chunk MyLibrary.alpha.js (alpha) 25 bytes [entry] [rendered]
    > ./alpha alpha
 ./alpha.js 25 bytes [built]
     entry ./alpha alpha
     used a library export
chunk MyLibrary.beta.js (beta) 24 bytes [entry] [rendered]
    > ./beta beta
 ./beta.js 24 bytes [built]
     entry ./beta beta
     used a library export
```

## Production mode

```
Hash: 0a1b2c3d4e5f6a7b8c9d
Version: webpack 5.0.0-beta.6
             Asset       Size
MyLibrary.alpha.js  429 bytes  [emitted]  [name: alpha]
 MyLibrary.beta.js  424 bytes  [emitted]  [name: beta]
Entrypoint alpha = MyLibrary.alpha.js
Entrypoint beta = MyLibrary.beta.js
chunk MyLibrary.alpha.js (alpha) 25 bytes [entry] [rendered]
    > ./alpha alpha
 ./alpha.js 25 bytes [built]
     entry ./alpha alpha
     used a library export
chunk MyLibrary.beta.js (beta) 24 bytes [entry] [rendered]
    > ./beta beta
 ./beta.js 24 bytes [built]
     entry ./beta beta
     used a library export
```