var LDAP = require('ldapjs');

var protocol = "ldap://";
var host = "...";
var post = 3268;
var dn = "cn=Van Nguyen,...";
var password = "some password";

var client = LDAP.createClient({
  url: protocol + host + ":" + port
});

//authenticate
client.bind(dn, password, function (err) {

  if (err) {
    throw err;
  }

  // authentication successful
  // do stuff

  // close connection when done
  client.unbind(function(err){

    if (err) {
      throw err;
    }
  });
});