An attempt to implement cmd parser like commander.

example.js

var mycommander = require('./mycommander');
console.log(mycommander);

console.log(process.argv.slice(2));

mycommander
  .option('-f, --foo i', 'Integer value for foo', parseInt, 0)
  .option('-b, --bar j', 'Integer value for bar', parseInt, 0)
  .option('-z, --baz', 'Boolean argument baz')
  .parse(process.argv.slice(2));

console.log(mycommander);
console.log(mycommander.foo.value);
console.log(mycommander.bar.value);
console.log(mycommander.baz.value);

mycommander.js

function MyCommander() {
  var self = this;

  self.option = function (cmdString, info, parserCb, defaultVal) {
    return option(self, cmdString, info, parserCb, defaultVal);
  };

  self.parse = function (args) {
    return parse(self, args);
  };

  self.prompt = prompt;

  //somehow cannot be functioning well
  //self.confirm = confirm;

  return this;
}

function option (thisObj, cmdString, info, parserCb, defaultVal) {
  var cmds = cmdString.split(',').map(function (option) {
    return option.trim();
  });
  var shortOpt;
  var idx = 0;
  if (cmds.length === 1 && cmds[0].indexOf('--') === 0) {
    idx = 0;
  }
  else if (cmds.length === 2 && cmds[1].indexOf('--') === 0) {
    idx = 1;
    shortOpt = cmds[0];
  }
  var memberName = cmds[idx].trim().substr(2).trim().split(' ')[0];
  memberName = memberName.split('=', 2)[0];
  thisObj[memberName] = {};
  thisObj[memberName].info = info;
  if (shortOpt) thisObj[shortOpt] = memberName;
  thisObj[memberName].parse = function (value) {
    var result = value? parserCb(value) :
      (defaultVal !== undefined) ? defaultVal : true;
    console.log('parse result:', result);
    return result;
  };
  return thisObj;
}

function parse(thisObj, args) {
  var prevArg = '';
  args.forEach(function (arg, idx) {
    arg = arg.trim();
    switch (optionTester(arg)) {
      case 'option':
        var somearg = getMemberName(thisObj, arg);
        if (prevArg) {
          executeParse(thisObj, prevArg);
        } else if (idx === args.length - 1) {
          executeParse(thisObj, somearg);
        }
        prevArg = somearg;
        break;

      case 'option-value':
        if (prevArg) {
          executeParse(thisObj, prevArg);
        }
        var optVal = arg.split('=', 2);
        var thearg = optVal[0];
        var value = optVal[1];
        var memberName;
        try {
          memberName = getMemberName(thisObj, thearg);
        } catch (error) {
          console.log(error);
        }
        thisObj[memberName].value = thisObj[memberName].parse(value);
        prevArg = '';
        break;

      case 'value':
        if (prevArg) {
          thisObj[prevArg].value = thisObj[prevArg].parse(arg);
          prevArg = '';
        }
        break;
    }
  });
  return thisObj;
}

function getMemberName (thisObj, opt) {
  if (opt.indexOf('--') === 0)
      return opt.substr(2);
  else if (opt.indexOf('-') === 0)
    return thisObj[opt];
  else
    throw new Error('No ' + opt + ' option defined.');
}

function executeParse (thisObj, memberName) {
  thisObj[memberName].value = thisObj[memberName].parse();
}

function optionTester (arg) {
  if (arg.indexOf('=') !== -1)
    return 'option-value';
  else if (arg.indexOf('--') === 0 || arg.indexOf('-') === 0)
    return 'option';
  else
    return 'value';
}

function prompt(question, cb) {
  console.log(question);
  process.stdin.on('data', cb);
  process.stdin.setEncoding('utf8');
  process.stdin.resume();
}

function confirm(question, cb) {
  prompt(question, function(data) {
    var trueAnswer = [ 'y', 'ok', 'yes', 'true' ];
    if (trueAnswer.indexOf(data.toLowerCase()) !== -1) {
      cb(true);
    }
    else {
      cb(false);
    }
  });
}

module.exports = (function () { return new MyCommander(); })();