gistfile1.js

var Sequelize = require('sequelize'),
	DAO = require('sequelize/lib/dao'),
	_increment = DAO.prototype.increment,
	_decrement = DAO.prototype.decrement;

DAO.prototype.increment = function(field, options) {
	var instance = this,
		by = (options && options.by) || options || 1;

	instance.set(field, instance.get(field) + by);
	return (_increment.apply(instance, arguments)).success(function () {
		if (by > 0) {
			instance.Model.runHooks('afterIncrement', instance, {field: field, by: by}, function () {

			});
		} else {
			instance.Model.runHooks('afterDecrement', instance, {field: field, by: by}, function () {

			});
		}
	});
};