Could you in generally explains the concepts involved in this change: Codeigniter/ jQuery/ AJAX to Laravel/ Angular JS/REST?

not sure what the benefit of using Laravel

The main benefits include RESTful routing, ORM, Exceptions, Symfony components for the data model, etc.  It's the fastest way I've ever found to get a server-side application running.  I think you will find it to be a great improvement over CodeIgniter.  If you want to see how easy it is to use Laravel, take a look at the Laravel documentation.  It really is that simple!  You may also want to consider Lumen, since it sounds like you just need an API to serve JSON responses.

For your own time-planning purposes, you will probably find that the Laravel part of things will get done very quickly.  But Angular has a learning curve that is not really a curve, so much as a wave.  You'll find yourself backtracking a lot as you look for examples of Angular best-practices.  Plan to devote the majority of your time to the client-side of the application.

But Angular has a learning curve that is not really a curve, so much as a wave.

Actually with Angular 1 it's a very tall brick wall. If you come from a php background Laravel is a cinch. But if you have a database or application server which dishes out JSON (or XML) and you use something like Node/Express/Passport to authenticate your client then Angular 1 is not so bad and with Angular 2 you can concentrate on making components which can be glued together to make apps that run literally anywhere - or at least that's the sales pitch from Google.

The main benefits include RESTful routing, ORM, Exceptions, Symfony components for the data model, etc

Laravel is an application framework. Angular is an application framework. There is nothing to say you can't mix them but generally you would pick one or the other. REST does not require a heavy framework to implement and ORM is not always the best fit for the application - with a client side framework that does not leave much for Laravel to do.

The point of my comment was - if you are going SPA with Angular then that is where your interface logic is going to sit communicating with a RESTful backend that could be based on pretty much anything.

But Angular has a learning curve that is not really a curve, so much as a wave.

Angular does have a steep learning curve but once you have grasped the methodology behind it - it makes things a lot easier. Some might argue that React is a better option with a shorter learning curve - but personally my feeling is that Angular brings some things that require extra effort in React that make the extra learning worth it.

You may also find some of this useful.
https://www.experts-exchange.com/articles/22519/Understanding-JSON-in-PHP-and-JavaScript-Applications.html

Hi for All

Thank you for the replies.

I'm carefully studying.

Thanks for help!