# @electron/get

> Download Electron release artifacts

[![CircleCI](https://circleci.com/gh/electron/get.svg?style=svg)](https://circleci.com/gh/electron/get)

## Usage

### Simple: Downloading an Electron Binary ZIP

```typescript
import { download } from '@electron/get';

// NB: Use this syntax within an async function, Node does not have support for
//     top-level await as of Node 12.
const zipFilePath = await download('4.0.4');
```

### Advanced: Downloading a macOS Electron Symbol File


```typescript
import { downloadArtifact } from '@electron/get';

// NB: Use this syntax within an async function, Node does not have support for
//     top-level await as of Node 12.
const zipFilePath = await downloadArtifact({
  version: '4.0.4',
  platform: 'darwin',
  artifactName: 'electron',
  artifactSuffix: 'symbols',
  arch: 'x64',
});
```

### Specifying a mirror

To specify another location to download Electron assets from, the following options are
available:

* `mirrorOptions` Object
  * `mirror` String (optional) - The base URL of the mirror to download from.
  * `nightlyMirror` String (optional) - The Electron nightly-specific mirror URL.
  * `customDir` String (optional) - The name of the directory to download from, often scoped by version number.
  * `customFilename` String (optional) - The name of the asset to download.
  * `resolveAssetURL` Function (optional) - A function allowing customization of the url used to download the asset.

Anatomy of a download URL, in terms of `mirrorOptions`:

```
https://github.com/electron/electron/releases/download/v4.0.4/electron-v4.0.4-linux-x64.zip
|                                                     |       |                           |
-------------------------------------------------------       -----------------------------
                        |                                                   |
              mirror / nightlyMirror                  |    |         customFilename
                                                       ------
                                                         ||
                                                      customDir
```

Example:

```typescript
import { download } from '@electron/get';

const zipFilePath = await download('4.0.4', {
  mirrorOptions: {
    mirror: 'https://mirror.example.com/electron/',
    customDir: 'custom',
    customFilename: 'unofficial-electron-linux.zip'
  }
});
// Will download from https://mirror.example.com/electron/custom/unofficial-electron-linux.zip

const nightlyZipFilePath = await download('8.0.0-nightly.20190901', {
  mirrorOptions: {
    nightlyMirror: 'https://nightly.example.com/',
    customDir: 'nightlies',
    customFilename: 'nightly-linux.zip'
  }
});
// Will download from https://nightly.example.com/nightlies/nightly-linux.zip
```

`customDir` can have the placeholder `{{ version }}`, which will be replaced by the version
specified (without the leading `v`). For example:

```javascript
const zipFilePath = await download('4.0.4', {
  mirrorOptions: {
    mirror: 'https://mirror.example.com/electron/',
    customDir: 'version-{{ version }}',
    platform: 'linux',
    arch: 'x64'
  }
});
// Will download from https://mirror.example.com/electron/version-4.0.4/electron-v4.0.4-linux-x64.zip
```

#### Using environment variables for mirror options
Mirror options can also be specified via the following environment variables:
* `ELECTRON_CUSTOM_DIR` - Specifies the custom directory to download from.
* `ELECTRON_CUSTOM_FILENAME` - Specifies the custom file name to download.
* `ELECTRON_MIRROR` - Specifies the URL of the server to download from if the version is not a nightly version.
* `ELECTRON_NIGHTLY_MIRROR` - Specifies the URL of the server to download from if the version is a nightly version.

### Overriding the version downloaded

The version downloaded can be overriden by setting the `ELECTRON_CUSTOM_VERSION` environment variable.
Setting this environment variable will override the version passed in to `download` or `downloadArtifact`.

## How It Works

This module downloads Electron to a known place on your system and caches it
so that future requests for that asset can be returned instantly.  The cache
locations are:

* Linux: `$XDG_CACHE_HOME` or `~/.cache/electron/`
* MacOS: `~/Library/Caches/electron/`
* Windows: `%LOCALAPPDATA%/electron/Cache` or `~/AppData/Local/electron/Cache/`

By default, the module uses [`got`](https://github.com/sindresorhus/got) as the
downloader. As a result, you can use the same [options](https://github.com/sindresorhus/got#options)
via `downloadOptions`.

### Progress Bar

By default, a progress bar is shown when downloading an artifact for more than 30 seconds. To
disable, set the `ELECTRON_GET_NO_PROGRESS` environment variable to any non-empty value, or set
`quiet` to `true` in `downloadOptions`. If you need to monitor progress yourself via the API, set
`getProgressCallback` in `downloadOptions`, which has the same function signature as `got`'s
[`downloadProgress` event callback](https://github.com/sindresorhus/got#ondownloadprogress-progress).

### Proxies

Downstream packages should utilize the `initializeProxy` function to add HTTP(S) proxy support. If
the environment variable `ELECTRON_GET_USE_PROXY` is set, it is called automatically. A different
proxy module is used, depending on the version of Node in use, and as such, there are slightly
different ways to set the proxy environment variables. For Node 10 and above,
[`global-agent`](https://github.com/gajus/global-agent#environment-variables) is used. Otherwise,
[`global-tunnel-ng`](https://github.com/np-maintain/global-tunnel#auto-config) is used. Refer to the
appropriate linked module to determine how to configure proxy support.
