build: be possible setup downloader for windows

lib/downloader.js

@@ -1,21 +1,22 @@
-var fs = require('fs')
-var path = require('path')
-var mkdirp = require('mkdirp')
-var request = require('request')
+'use strict'
+
+const request = require('request')
+const mkdirp = require('mkdirp')
+const path = require('path')
+const fs = require('fs')
+
+const [, , ...flags] = process.argv
+
+const isWin = flags.includes('--platform=windows') || require('./util').isWin
 
 // First, look for the download link.
-var dir, filePath
-var isWin = !!(
- process.platform === 'win32' || process.env.NODE_PLATFORM === 'windows'
-)
-var defaultBin = path.join(__dirname, '..', 'bin')
-var defaultPath = path.join(defaultBin, 'details')
-var url = 'https://yt-dl.org/downloads/latest/youtube-dl'
+let dir, filePath
+const defaultBin = path.join(__dirname, '..', 'bin')
+const defaultPath = path.join(defaultBin, 'details')
+const url = 'https://yt-dl.org/downloads/latest/youtube-dl'
 
 function download (url, callback) {
- 'use strict'
-
- var status = null
+ let status
 
  // download the correct version of the binary based on the platform
  url = exec(url)
@@ -32,9 +33,9 @@ function download (url, callback) {
  )
  }
 
- var url = res.headers.location
- var downloadFile = request.get(url)
- var newVersion = /yt-dl\.org\/downloads\/(\d{4}\.\d\d\.\d\d(\.\d)?)\/youtube-dl/.exec(
+ const url = res.headers.location
+ const downloadFile = request.get(url)
+ const newVersion = /yt-dl\.org\/downloads\/(\d{4}\.\d\d\.\d\d(\.\d)?)\/youtube-dl/.exec(
  url
  )[1]
 
@@ -56,23 +57,16 @@ function download (url, callback) {
  })
 }
 
-function exec (path) {
- 'use strict'
- return isWin ? path + '.exe' : path
-}
+const exec = path => (isWin ? path + '.exe' : path)
 
 function createBase (binDir) {
- 'use strict'
  dir = binDir || defaultBin
  mkdirp.sync(dir)
- if (binDir) {
- mkdirp.sync(defaultBin)
- }
+ if (binDir) mkdirp.sync(defaultBin)
  filePath = path.join(dir, exec('youtube-dl'))
 }
 
 function downloader (binDir, callback) {
- 'use strict'
  if (typeof binDir === 'function') {
  callback = binDir
  binDir = null
@@ -81,9 +75,7 @@ function downloader (binDir, callback) {
  createBase(binDir)
 
  download(url, function error (err, newVersion) {
- if (err) {
- return callback(err)
- }
+ if (err) return callback(err)
  fs.writeFileSync(
  defaultPath,
  JSON.stringify({
@@ -93,7 +85,7 @@ function downloader (binDir, callback) {
  }),
  'utf8'
  )
- callback(null, 'Downloaded youtube-dl ' + newVersion)
+ return callback(null, 'Downloaded youtube-dl ' + newVersion)
  })
 }