test.js

var stdin = process.openStdin();
stdin.on('data', parse);
var commands = {};
function parse(it) {
    var parts = it.split(' ');
    var commandIdx = Object.keys(commands).indexOf(parts[0]);
    if (commandIdx > -1) {
        commands[commandIdx].apply(null, parts.slice(1));
    }
    else {
        console.log('Command not found');
    }
}

commands['adder'] = function() {
    console.log([].slice.call(arguments).reduce(function(a, b) { return a + b; }, 0);
};