PHP-to-Javascript | converting simple PHP objects/code to Javascript | REST library

According to this post, you can keep a connection open with the server to listen for any changes. Is there any possible way to do it with jQuery's $.get() or $.ajax() methods?

I'm trying to get my google maps app to wait for an answer from an ajax call from a db call using php. I know I need to use callbacks but I'm unsure how to implement them in this case since geocoder api is also async.

I tried answer from How to pass variables and data from PHP to JavaScript? and Using gettext with Javascript from PHP via XMLHttpRequest but I'm unsure how to edit it to work with my case.

db.php

I have read the following posts, but they are a little over the top for me. I think I'm trying to do something fairly simple, and would like some guidance.

How to pass variables and data from PHP to JavaScript?

passing PHP variables across javascript windows.open to another PHP page

Posting a php variable to a new window

Here is the case:

I have a php script which is very simple, it calls another script and passes 2 variables:

I tried here and here - without success

I have a php file which needs to pass an array to an external javascript file. I'm trying to do it using AJAX because it seems like the proper way to do so. I'm trying to do an echo json_encode($exif) and then get it in the js but the json is printed on my current page. How can I achieve what I'm doing and what's the proper way to do it?

I'm trying to do the first solution of this answer How to pass variables and data from PHP to JavaScript? but I don't see how to integrate the php part so that it doesn't show up on my page.

Here is the php code. I need to pass the array while building my view. Therefore when I do the echo, the whole array is displayed on the page.

I have a php page that queries a mysql db and return a .json file.

I want this page to be called within a coffeescript page, but I don't understand the syntax to accomplish this.

I have seen here that in plain js you can do:

I'm trying to learn how to to use javascript(with or without jquery) in an HTML page on the same server as a php class, to initialize the PHP class, then call its getLinks() method and pass its return array of links to a java script array.

I was hoping that this could be done without having any php code on the index page at all.

I have seen a few examples, including this great one Here, but it doesn't seem to address certain particulars such as;

1)How would I even write an include on a page with no php? 2)How would I instantiate a php class , and call a specific method? 2)I can make a PHP helper file to do the instantiations, but then I would still need to call a method, how would this be done? 3)How would I use jQuery to make a GET request and call the function from the request?

If this can not be done without adding php code to the index page, please let me know this

My PHP Code: