Promise friendly node pg wrapper

pg-createdb-promise.js

var createDb = function(addr){
  console.log("connecting to", addr);
  var client = new pg.Client(addr);
  var qfn = client.query;
  client.query = function(){
    var len = arguments.length;
    if(typeof arguments[len-1] === "function"){
      var callback = arguments[len-1];
      arguments[len-1] = function(error, result){
        if(error){
          throw error;
        }else{
          callback.call(this, result);
        }
      };
    }
    var result = qfn.apply(this, arguments)
    result.on("error", exit);
  }
  
  client.executeAsync = function(){
    var THIS = this;
    var args = [].slice.call(arguments);
    return new Promise(function(resolve, reject){
      args.push(function(error, result){
        resolve(result);
      })
      THIS.query.apply(THIS, args)
    });
  }
  client.queryAsync = function(){
    var THIS = this;
    var args =  [].slice.call(arguments);
    var len = args.length;
    if(typeof args[len-1] === "function"){
      return new Promise(function(resolve, reject){
        var cb = args[len-1];
        args[len-1] = function(result){
          resolve(cb(result));
        }
        THIS.query.apply(THIS, args)
      });
    }else{
        var q = THIS.query.apply(THIS, args);
        q.onRow = function(callback){
          q.on("row", callback);
        };
        q.onEnd = function(callback){
          return new Promise(function(resolve, reject){
            q.on("end", function(){
              resolve(callback.apply());
            });
          });
        }
        return q;
    }
  }
  client.on('error', function(error) {
    console.log("got error");
    throw error;
  })
  client.connect();
  return client;
}