This is Node.js library for easy operation with Slack API.

It also exposes all opportunities of Slack's Real Time Messaging API.

npm install slackbots

• start - event fired, when Real Time Messaging API is started (via websocket),
• message - event fired, when something happens in Slack. Description of all events here,
• open - websocket connection is open and ready to communicate,
• close - websocket connection is closed.
• error - an error occurred while connecting to Slack

• getChannels() (return: promise) - returns a list of all channels in the team,
• getGroups() (return: promise) - returns a list of all groups in the team,
• getUsers() (return: promise) - returns a list of all users in the team,
• getImChannels() (return: promise) - returns a list of bots direct message channels in the team,
• getChannel(name) (return: promise) - gets channel by name,
• getGroup(name) (return: promise) - gets group by name,
• getUser(name) (return: promise) - gets user by name,
• getUserByEmail(name) (return: promise) - gets user by name,
• getChannelId(name) (return: promise) - gets channel ID by name,
• getGroupId(name) (return: promise) - gets group ID by name,
• getUserId(name) (return: promise) - gets user ID by name,
• getChatId(name) (return: promise) - it returns or opens and returns a direct message channel ID,
• postEphemeral(id, user, text, params) (return: promise) - posts an ephemeral message to channel and user by ID,
• postMessage(id, text, params) (return: promise) - posts a message to channel | group | user by ID,
• updateMessage(channelId, timestamp, text, params) (return: promise) - updates a message in a channel,
• postTo(name, message [, params, callback]) (return: promise) - posts a message to channel | group | user by name,
• postMessageToUser(name, message [, params, callback]) (return: promise) - posts a direct message by user name,
• postMessageToGroup(name, message [, params, callback]) (return: promise) - posts a message to private group by name,
• postMessageToChannel(name, message [, params, callback]) (return: promise) - posts a message to channel by name.
• openIm(userId) (return: promise) - opens a direct message channel with another member in the team

var SlackBot = require('slackbots');

// create a bot
var bot = new SlackBot({
    token: 'xoxb-012345678-ABC1DFG2HIJ3', // Add a bot https://my.slack.com/services/new/bot and put the token 
    name: 'My Bot'
});

bot.on('start', function() {
    // more information about additional params https://api.slack.com/methods/chat.postMessage
    var params = {
        icon_emoji: ':cat:'
    };
    
    // define channel, where bot exist. You can adjust it there https://my.slack.com/services 
    bot.postMessageToChannel('general', 'meow!', params);
    
    // define existing username instead of 'user_name'
    bot.postMessageToUser('user_name', 'meow!', params); 
    
    // If you add a 'slackbot' property, 
    // you will post to another user's slackbot channel instead of a direct message
    bot.postMessageToUser('user_name', 'meow!', { 'slackbot': true, icon_emoji: ':cat:' }); 
    
    // define private group instead of 'private_group', where bot exist
    bot.postMessageToGroup('private_group', 'meow!', params); 
});

PROFIT!

/**
 * @param {object} data
 */
bot.on('message', function(data) {
    // all ingoing events https://api.slack.com/rtm
    console.log(data);
});

###Response Handler The simplest way for handling response is callback function, which is specified as a last argument:

bot.postMessageToUser('user1', 'hi', function(data) {/* ... */});
bot.postMessageToUser('user1', 'hi', params, function(data) {/* ... */});

But also you can use promises.

Error:

bot.postMessageToUser('user1', 'hi').fail(function(data) {
    //data = { ok: false, error: 'user_not_found' }
})

Success:

bot.postMessageToUser('user', 'hi').then(function(data) {
    // ...
})

Error and Success:

bot.postMessageToUser('user', 'hi').always(function(data) {
    // ...
})