discord.js

// IN main.js

var Discord = require("discord.js");
var bot = new Discord.Client();

// Store all the commands from commands.js in a variable
var commands = require("./commands");

// Prefix that all commands must start with
var commandPrefix = "?";

function handleCommand(message) {
	// Easy access to message author
	var sender = message.author; 
	
	// Easy access to text of the message
	var content = message.content.trim(); 
		
	// Split up the text of the message by " "  
	var parts = content.split(" ");
	
	// Get rid of the first part (the command name)
	var args = parts.slice(1, parts.length); 
	
	// Take the first part (the command name)
	var command = parts[0].replace(commandPrefix, ""); 
	
	console.log(command + " command by " + sender.username + ": '"+content+"'");
	
	// See if a function for this command exists in the command object (from commands.js)
	if(commands[command] !== undefined) {
		// Run the command
		commands[command](bot, message, args);
	} else {
		// The command doesn't exist!
		bot.reply(message, "Command not recognized!");
	}
	
}

bot.on("message", function(message) {
	// Check if message is command
	if(message.content.startsWith(commandPrefix)) {
		handleCommand(message);
	}else{
		
	}
});

bot.login("username", "password");

// -----------------

// IN commands.js

var commands = {};

commands.echo = function(bot, message, args) {
	bot.reply(message, args.join(" "));
}

commands.help = function(bot, message, args) {
	var help = ["**Command List**"];
	for(var com in commands) {
		help.push("`-` "+com);
	}
	bot.sendMessage(message.channel, help.join("\n"));
}

module.exports = commands;