💥 Switch to Promise based interface

Migration Guide:

Instead of taking a callback, the exposed functions now returns a Promise.

Author: LinusU

impl/darwin.js

@@ -1,51 +1,21 @@
-const { spawn } = require('child_process')
+const execa = require('execa')
 
-const osascript = function (cmd, cb) {
-  let ret = ''
-  let err = null
-  const p = spawn('osascript', ['-e', cmd])
-
-  p.stdout.on('data', function (data) {
-    ret += data
-  })
-
-  p.stderr.on('data', function (data) {
-    err = new Error('Apple Script Error: ' + data)
-  })
-
-  p.on('close', function () {
-    cb(err, ret.trim())
-  })
+function osascript (cmd) {
+  return execa.stdout('osascript', ['-e', cmd], { preferLocal: false })
 }
 
-module.exports.getVolume = function (cb) {
-  osascript('output volume of (get volume settings)', function (err, vol) {
-    if (err) {
-      cb(err)
-    } else {
-      cb(null, parseInt(vol, 10))
-    }
-  })
+exports.getVolume = function () {
+  return osascript('output volume of (get volume settings)').then(vol => parseInt(vol, 10))
 }
 
-module.exports.setVolume = function (val, cb) {
-  osascript('set volume output volume ' + val, function (err) {
-    cb(err)
-  })
+exports.setVolume = function (val) {
+  return osascript('set volume output volume ' + val).then(() => undefined)
 }
 
-module.exports.getMuted = function (cb) {
-  osascript('output muted of (get volume settings)', function (err, mute) {
-    if (err) {
-      cb(err)
-    } else {
-      cb(null, (mute === 'true'))
-    }
-  })
+exports.getMuted = function () {
+  return osascript('output muted of (get volume settings)').then(mute => (mute === 'true'))
 }
 
-module.exports.setMuted = function (val, cb) {
-  osascript('set volume ' + (val ? 'with' : 'without') + ' output muted', function (err) {
-    cb(err)
-  })
+exports.setMuted = function (val) {
+  return osascript('set volume ' + (val ? 'with' : 'without') + ' output muted').then(() => undefined)
 }

impl/linux.js

@@ -1,104 +1,56 @@
-const { spawn } = require('child_process')
+const execa = require('execa')
 
-const amixer = function (args, cb) {
-  let ret = ''
-  let err = null
-  const p = spawn('amixer', args)
+function amixer (...args) {
+  return execa.stdout('amixer', args, { preferLocal: false })
+}
+
+let defaultDeviceCache = null
+const reDefaultDevice = /Simple mixer control '([a-z0-9 -]+)',[0-9]+/i
 
-  p.stdout.on('data', function (data) {
-    ret += data
-  })
+function parseDefaultDevice (data) {
+  const result = reDefaultDevice.exec(data)
 
-  p.stderr.on('data', function (data) {
-    err = new Error('Alsa Mixer Error: ' + data)
-  })
+  if (result === null) {
+    throw new Error('Alsa Mixer Error: failed to parse output')
+  }
 
-  p.on('close', function () {
-    cb(err, ret.trim())
-  })
+  return result[1]
 }
 
-const reDefaultDevice = /Simple mixer control '([a-z0-9 -]+)',[0-9]+/i
-let defaultDeviceCache = null
-const defaultDevice = function (cb) {
-  if (defaultDeviceCache === null) {
-    amixer([], function (err, data) {
-      if (err) {
-        cb(err)
-      } else {
-        let res = reDefaultDevice.exec(data)
-        if (res === null) {
-          cb(new Error('Alsa Mixer Error: failed to parse output'))
-        } else {
-          defaultDeviceCache = res[1]
-          cb(null, defaultDeviceCache)
-        }
-      }
-    })
-  } else {
-    cb(null, defaultDeviceCache)
-  }
+function getDefaultDevice () {
+  if (defaultDeviceCache) return Promise.resolve(defaultDeviceCache)
+
+  return amixer().then(data => (defaultDeviceCache = parseDefaultDevice(data)))
 }
 
 const reInfo = /[a-z][a-z ]*: Playback [0-9-]+ \[([0-9]+)%\] (?:[[0-9.-]+dB\] )?\[(on|off)\]/i
-const getInfo = function (cb) {
-  defaultDevice(function (err, dev) {
-    if (err) {
-      cb(err)
-    } else {
-      amixer(['get', dev], function (err, data) {
-        if (err) {
-          cb(err)
-        } else {
-          let res = reInfo.exec(data)
-          if (res === null) {
-            cb(new Error('Alsa Mixer Error: failed to parse output'))
-          } else {
-            cb(null, {
-              volume: parseInt(res[1], 10),
-              muted: (res[2] === 'off')
-            })
-          }
-        }
-      })
-    }
-  })
+
+function parseInfo (data) {
+  const result = reInfo.exec(data)
+
+  if (result === null) {
+    throw new Error('Alsa Mixer Error: failed to parse output')
+  }
+
+  return { volume: parseInt(result[1], 10), muted: (result[2] === 'off') }
+}
+
+function getInfo () {
+  return getDefaultDevice().then(dev => amixer('get', dev)).then(data => parseInfo(data))
 }
 
-module.exports.getVolume = function (cb) {
-  getInfo(function (err, obj) {
-    if (err) {
-      cb(err)
-    } else {
-      cb(null, obj.volume)
-    }
-  })
+exports.getVolume = function () {
+  return getInfo().then(info => info.volume)
 }
 
-module.exports.setVolume = function (val, cb) {
-  defaultDevice(function (err, dev) {
-    if (err) {
-      cb(err)
-    } else {
-      amixer(['set', dev, val + '%'], function (err) {
-        cb(err)
-      })
-    }
-  })
+module.exports.setVolume = function (val) {
+  return getDefaultDevice().then(dev => amixer('set', dev, val + '%')).then(() => undefined)
 }
 
 module.exports.getMuted = function (cb) {
-  getInfo(function (err, obj) {
-    if (err) {
-      cb(err)
-    } else {
-      cb(null, obj.muted)
-    }
-  })
+  return getInfo().then(info => info.muted)
 }
 
 module.exports.setMuted = function (val, cb) {
-  amixer(['set', 'PCM', (val ? 'mute' : 'unmute')], function (err) {
-    cb(err)
-  })
+  return amixer('set', 'PCM', (val ? 'mute' : 'unmute')).then(() => undefined)
 }

impl/windows/index.js

@@ -1,85 +1,32 @@
-const { spawn } = require('child_process')
+const execa = require('execa')
 const path = require('path')
 
-const executable = path.join(__dirname, 'adjust_get_current_system_volume_vista_plus.exe')
+const executablePath = path.join(__dirname, 'adjust_get_current_system_volume_vista_plus.exe')
 
-const runProgram = function (args, done) {
-  args = args === '' ? [] : args.toString().split(' ')
-  done = done || function () {}
-
-  let ret = ''
-  let err = null
-  const p = spawn(executable, args)
-
-  p.stdout.on('data', function (data) {
-    ret += data
-  })
-
-  p.stderr.on('data', function (data) {
-    err = new Error('Windows Script Error: ' + data)
-  })
-
-  p.on('close', function () {
-    if (err) return done(err)
-
-    return done(null, ret.trim())
-  })
+function runProgram (...args) {
+  return execa.stdout(executablePath, args)
 }
 
-const getVolumeInfo = function (done) {
-  done = done || function () {}
-
-  runProgram('', function (err, strArgs) {
-    if (err) return done(err)
+function getVolumeInfo () {
+  return runProgram().then((data) => {
+    const args = data.split(' ')
 
-    const args = strArgs.split(' ')
-    const info = {
-      volume: parseInt(args[0]),
-      isMuted: !!parseInt(args[1])
-    }
-
-    return done(null, info)
+    return { volume: parseInt(args[0], 10), isMuted: Boolean(parseInt(args[1], 10)) }
   })
 }
 
-module.exports.getVolume = function (done) {
-  done = done || function () {}
-
-  getVolumeInfo(function (err, info) {
-    if (err) return done(err)
-
-    return done(null, info.volume)
-  })
+exports.getVolume = function () {
+  return getVolumeInfo().then(info => info.volume)
 }
 
-module.exports.setVolume = function (val, done) {
-  val = val || 0
-  done = done || function () {}
-
-  runProgram(val, function (err) {
-    if (err) return done(err)
-
-    return done(null)
-  })
+exports.setVolume = function (val) {
+  return runProgram(String(val)).then(() => undefined)
 }
 
-module.exports.getMuted = function (done) {
-  done = done || function () {}
-
-  getVolumeInfo(function (err, info) {
-    if (err) return done(err)
-
-    return done(null, info.isMuted)
-  })
+exports.getMuted = function () {
+  return getVolumeInfo().then(info => info.isMuted)
 }
 
-module.exports.setMuted = function (val, done) {
-  val = val ? 'mute' : 'unmute'
-  done = done || function () {}
-
-  runProgram(val, function (err) {
-    if (err) return done(err)
-
-    return done(null)
-  })
+exports.setMuted = function (val) {
+  return runProgram(val ? 'mute' : 'unmute').then(() => undefined)
 }

index.js

@@ -16,16 +16,16 @@ switch (os.type()) {
 }
 
 module.exports = {
-  setVolume (volume, cb) {
-    impl.setVolume(volume, cb)
+  setVolume (volume) {
+    return impl.setVolume(volume)
   },
-  getVolume (cb) {
-    impl.getVolume(cb)
+  getVolume () {
+    return impl.getVolume()
   },
-  setMuted (muted, cb) {
-    impl.setMuted(muted, cb)
+  setMuted (muted) {
+    return impl.setMuted(muted)
   },
-  getMuted (cb) {
-    impl.getMuted(cb)
+  getMuted () {
+    return impl.getMuted()
   }
 }