npm install slack-node

var Slack = require('slack-node');

domain = "--your-slack-subdomain--";
webhookToken = "--your-slack-webhook--";

slack = new Slack(webhookToken, domain);

slack.webhook({
  channel: "#general",
  username: "webhookbot",
  text: "This is posted to #general and comes from a bot named webhookbot."
}, function(err, response) {
  console.log(response);
});

var Slack = require('slack-node');

domain = "--your-slack-subdomain--";
webhookToken = "--your-slack-webhook--";

slack = new Slack(webhookToken, domain);

// slack emoji
slack.webhook({
  channel: "#general",
  username: "webhookbot",
  icon_emoji: ":ghost:"
}, function(err, response) {
  console.log(response);
});

// URL image
slack.webhook({
  channel: "#general",
  username: "webhookbot",
  icon_emoji: "http://icons.iconarchive.com/icons/rokey/popo-emotions/128/after-boom-icon.png"
}, function(err, response) {
  console.log(response);
});

var Slack = require('slack-node');
apiToken = "-- api token --";

slack = new Slack(apiToken);

slack.api("users.list", function(err, response) {
  console.log(response);
});