how to regenerate minify js and css from source code of js grid library

I have js grid source code downloaded from their website and want to tune it as per my need, for example it has a div with class container at very beginning after it loads the grid with data and I want to change that class to something like <div class="new_container"></div>. There is a jsgrid.min.js file I can't change in it. After some research I realize I have to change in jsgrid.js file which is responsible of generating html then there is some way I don't know what and how of creating or regenerating jsgrid.min.js and jsgrid.min.css so I can use it in my code. Please guide me if any one know, suggest me articles so I can study them step by step and get to know this technique or whatever it is called :)

here is directory overview of js Grid source code I am using laravel 5 for php

via Chebli Mohamed