Node.js 操作 OSX 系统麦克风、扬声器音量

最近几年 Electron 很火，公司也正好有个项目想做跨平台客户端，大家研究了一下就选择了 Electron，第一次做 js 的项目遇到了不少坑，不过也都一点点解决了。
因为项目中需要对用户录音，HTML5 中的 API 又不支持调整麦克风音量，所以就对 Node js 操作 osx 系统麦克风、扬声器音量了解了一下，一开始在 npm（https://www.npmjs.com/）中找了很多包都是只能操作扬声器音量的，无法操作麦克风的音量，本来已经打算放弃了，缺无意间在网上看到 osx 系统下有自己的脚本——AppleScript，查看了官方文档之后发现 AppleScript 确实可以控制系统的音量（https://developer.apple.com/library/archive/documentation/AppleScript/Conceptual/AppleScriptLangGuide/reference/ASLR_cmds.html#//apple_ref/doc/uid/TP40000983-CH216-SW41），之后又到 npm 中搜索一番找到了 osx-volume-controls（https://www.npmjs.com/package/osx-volume-controls）这个包，经过改造终于实现了这个功能

因为要使用到 applescript 这个包，所以需要执行下面的命令：

 npm i -save applescript 

具体类实现代码如下：

var applescript = require("applescript");

var scripts = {
  state: "input volume of (get volume settings) & output volume of (get volume settings) & output muted of (get volume settings)",
  volumeState: "output volume of (get volume settings)",
  inputState: "input volume of (get volume settings)",
  outputState: "output volume of (get volume settings)",
  muteState: "output muted of (get volume settings)",
  setOutput: "set volume output volume %s --100%",
  setInput: "set volume input volume %s --100%",
  increase: "set volume output volume (output volume of (get volume settings) + 10) --100%",
  decrease: "set volume output volume (output volume of (get volume settings) - 10) --100%",
  mute: "set volume with output muted",
  unmute: "set volume without output muted"
};

var exec = function (script, callback) {
  if (!callback) callback = function () {};
  applescript.execString(script, callback);
};

var getScript = function (scriptName, param) {
  var script = scripts[scriptName];
  if (typeof param !== "undefined") script = script.replace("%s", param);
  return script;
};

exports.state = function (callback) {
  return exec(getScript("state"), callback);
};

exports.volumeState = function (callback) {
  return exec(getScript("volumeState"), callback);
};

exports.inputState = function (callback) {
  return exec(getScript("inputState"), callback);
};

exports.outputState = function (callback) {
  return exec(getScript("outputState"), callback);
};

exports.muteState = function (callback) {
  return exec(getScript("muteState"), callback);
};

exports.setOutput = function (volume, callback) {
  return exec(getScript("setOutput", volume), callback);
};

exports.setInput = function (volume, callback) {
  return exec(getScript("setInput", volume), callback);
};

exports.increase = function (callback) {
  return exec(getScript("increase"), callback);
};

exports.decrease = function (callback) {
  return exec(getScript("decrease"), callback);
};

exports.mute = function (callback) {
  return exec(getScript("mute"), callback);
};

exports.unmute = function (callback) {
  return exec(getScript("unmute"), callback);
};

使用方法（可以参照osx-volume-controls文档）：

    import volume from "../../utils/osxVolume.js";
    volume.setInput(volumecontrol);