vue-hello/node_modules/module-alias/README.md

# module-alias
[![NPM Version][npm-image]][npm-url]
[![Build Status][travis-image]][travis-url]

Create aliases of directories and register custom module paths in NodeJS like a boss!

No more shit-coding paths in Node like so:

```js
require('../../../../some/very/deep/module')
```
Enough of this madness!

Just create an alias and do it the right way:

```js
var module = require('@deep/module')
// Or ES6
import module from '@deep/module'
```

It also allows you to register directories that will act just like `node_modules` but with your own private modules, so that you can access them directly:

```js
require('my_private_module');
// Or ES6
import module from 'my_private_module'
```

**WARNING:** This module should not be used in other npm modules since it modifies the default `require` behavior! It is designed to be used for development of final projects i.e. web-sites, applications etc.

## Install

```
npm i --save module-alias
```

## Usage

Add your custom configuration to your `package.json` (in your application's root)

```js
// Aliases
"_moduleAliases": {
  "@root"      : ".", // Application's root
  "@deep"      : "src/some/very/deep/directory/or/file",
  "@my_module" : "lib/some-file.js",
  "something"  : "src/foo", // Or without @. Actually, it could be any string
}

// Custom module directories, just like `node_modules` but with your private modules (optional)
"_moduleDirectories": ["node_modules_custom"],
```

Then add this line at the very main file of your app, before any code

```js
require('module-alias/register')
```

**And you're all set!** Now you can do stuff like:

```js
require('something')
const module = require('@root/some-module')
const veryDeepModule = require('@deep/my-module')
const customModule = require('my_private_module') // module from `node_modules_custom` directory

// Or ES6
import 'something'
import module from '@root/some-module'
import veryDeepModule from '@deep/my-module'
import customModule from 'my_private_module' // module from `node_modules_custom` directory
```

## Advanced usage

If you don't want to modify your `package.json` or you just prefer to set it all up programmatically, then the following methods are available for you:

* `addAlias('alias', 'target_path')` - register a single alias
* `addAliases({ 'alias': 'target_path', ... }) ` - register multiple aliases
* `addPath(path)` - Register custom modules directory (like node_modules, but with your own modules)

_Examples:_
```js
const moduleAlias = require('module-alias')

//
// Register alias
//
moduleAlias.addAlias('@client', __dirname + '/src/client')

// Or multiple aliases
moduleAlias.addAliases({
  '@root'  : __dirname,
  '@client': __dirname + '/src/client',
  ...
})

// Custom handler function (starting from v2.1)
moduleAlias.addAlias('@src', (fromPath, request, alias) => {
  // fromPath - Full path of the file from which `require` was called
  // request - The path (first argument) that was passed into `require`
  // alias - The same alias that was passed as first argument to `addAlias` (`@src` in this case)

  // Return any custom target path for the `@src` alias depending on arguments
  if (fromPath.startsWith(__dirname + '/others')) return __dirname + '/others'
  return __dirname + '/src'
})

//
// Register custom modules directory
//
moduleAlias.addPath(__dirname + '/node_modules_custom')
moduleAlias.addPath(__dirname + '/src')

//
// Import settings from a specific package.json
//
moduleAlias(__dirname + '/package.json')

// Or let module-alias to figure where your package.json is
// located. By default it will look in the same directory
// where you have your node_modules (application's root)
moduleAlias()
```

## Usage with WebPack

Luckily, WebPack has a built in support for aliases and custom modules directories so it's easy to make it work on the client side as well!

```js
// webpack.config.js
const npm_package = require('./package.json')

module.exports = {
  entry: { ... },
  resolve: {
    root: __dirname,
    alias: npm_package._moduleAliases || {},
    modules: npm_package._moduleDirectories || [] // eg: ["node_modules", "node_modules_custom", "src"]
  }
}
```

## How it works?

In order to register an alias it modifies the internal `Module._resolveFilename` method so that when you use `require` or `import` it first checks whether the given string starts with one of the registered aliases, if so, it replaces the alias in the string with the target path of the alias.

In order to register a custom modules path (`addPath`) it modifies the internal `Module._nodeModulePaths` method so that the given directory then acts like it's the `node_modules` directory.

[npm-image]: https://img.shields.io/npm/v/module-alias.svg
[npm-url]: https://npmjs.org/package/module-alias
[travis-image]: https://img.shields.io/travis/ilearnio/module-alias/master.svg
[travis-url]: https://travis-ci.org/ilearnio/module-alias

## Refactor your code (for already existing projects)

If you are using this on an existing project, you can use [relative-to-alias](https://github.com/s-yadav/relative-to-alias) to refactor your code to start using aliases.