Adding pagination to knex.js

pagination.js

var Knex = require('knex');
var Promise = require('bluebird');

Object.assign(Knex.Client.prototype.QueryBuilder.prototype, {
    paginate(per_page, current_page) {
      var pagination = {};
      var per_page = +per_page || 8;
      var page = +current_page || 1;
      if ( page < 1 ) page = 1;
      var offset = (page - 1)  * per_page;
      return Promise.all([
          this.clone().count('* as count').first(),
          this.offset(offset).limit(per_page)
        ]).then(function(values) {
            var count = values[0].count;
            var rows = values[1];
            pagination.data = rows;
            pagination.total = count;
            pagination.per_page = per_page;
            pagination.offset = offset;
            pagination.to = offset + rows.length;
            pagination.last_page = Math.ceil(count / per_page);
            pagination.current_page = page;
            pagination.from = offset;
            return pagination;
        });
      }); 
    }
});