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How to pass resource from php to javascript

So I have three different separate files:
functions.php (all functions for the database)
main.html (my main program)
main.js (all javascript functions)
Now, I want to call a function in PHP through AJAX. To do that, I need to pass $conn.
$conn = sqlsrv_connect($serverName, $connectionInfo);
It's a resource, so I can't use json_encode.
The way I set the everything up now is that the php-file is required in the html so I can use the functions and when I change the
value of a dropdown, the js is called.
How can I pass the $conn variable to Javascript?
Regards

It doesn't work like that.
You should never be directly making calls to the database from the front-end.
Think of it as three separate levels. Your HTML/JS is the front-end, your PHP is your server, and your Database is on its own level.
So when the user does something on the front-end, say changes the value of a field and you want to update that in the database the following actions should happen:
Event triggers on JS
AJAX is called as a result of the event being triggered
PHP server receives the AJAX request and executes code to modify database
(optional) PHP server sends something back to the front-end to tell it that the request was successful
Read up on the concept of MVC: https://developer.mozilla.org/en-US/docs/Web/Apps/Fundamentals/Modern_web_app_architecture/MVC_architecture

Try this in php code as I assume functions.php
$conn = sqlsrv_connect($serverName, $connectionInfo);
echo $conn;//Don't try echo anything other
In Javascript
$.ajax({
type: "POST",
url: "functions.php",
success: function(data)
{
var conn = data; // here is your conn which comes from php file
}
});

First of all include jquery latest version from cdn
Create an API Url, and use POST method
site.com/api/insert.php // to insert into table
Use $.post() api of jquery to send data
var url = ""; // enter your URL HERE
var postData = {}; // object of post data with table name, cols and values
$.post(url, postData, function(data, status) {
// do what ever you want with data
})
ps: you can also create diff insertion / selection / update / delete api for different table. (recommended)
Read more about $.post() here

Making Json objects using Session Variables in another file

I was trying to make a Json Object of some variables Which I am using as Session variables, But I am not geting the proper Response To make it as Json Object ..
Some Code which I tried (for Reference) Sharing Below..
//Passing the Variable To another PHP File
session_start();
$_SESSION['EmailIds']=$strEmailIds;
$_SESSION['SCHOOL_NAME']=$SCHOOL_NAME;
//sending data to another php page ..
header('Location: ../SecondPage.php');
In second file SecondPage.php Where i was Using This Session..
session_start();
$SCHOOL_NAME = $_SESSION['SCHOOL_NAME'];//1
$EmailIds= $_SESSION['EmailIds'];//1 <br>
Now trying to make this Session Variable in Json OBject...????
var OBJ = jsonObj.(SCHOOL_NAME+EmailIds);// Confuse with THis Line<br>
Actuaaly Not Getting What is the Good Approach To make this variables as Json Objects..
AS I Made this Json Object I can Use This AS another Purpose Like to send as Ajax Data and etc..

You can use json_encode method like this :
$someArray; //can be array of your values or $_SESSION
$jsonObj = json_encode($someArray);

get session data in an array like :
$data['SCHOOL_NAME'] = $_SESSION['SCHOOL_NAME'];
$data['EmailIds']= $_SESSION['EmailIds'];
then encode it like
$json_obj = json_encode($data);

How to pass a value from JavaScript in php?

Translate translator from Google. So that did not swear if something is not clear. Itself from Russia.
The question arose. How to pass the value of the alert in the javascript in the variable $ value in php, and write it in the case file. And another question: how to hide the alert? or use instead to visually it was not visible, but the value was passed?
//a lot of code
{
console.log(data);
alert(data['value']);
}
});
So. Also there is a PHP script that writes logs (current page and the previous one) to a file. According to this principle here:
//a lot of code
$home = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$referer = $_SERVER['HTTP_REFERER'];
$value = how the value of the java script to convey here?;
$lines = file($file);
while(count($lines) > $sum) array_shift($lines);
$lines[] = $home."|".$referer."|".$value."|\r\n";
file_put_contents($file, $lines);
It is necessary that the value of js is transferred to the php-script and write to the file. How to do it? Prompt please. I am a novice in all of this.

PHP scripts run before your javascript, which means that you can pass your php variables into javascript, but not the other way around. However, you can make an AJAX POST request from JavaScript to your PHP script, and grab the POST data in PHP through the global $_POST variable.
Assuming you use jQuery, your JavaScript would look something like:
// assign data object:
var data = { value: "test" };
// send it to your PHP script via AJAX POST request:
$.ajax({
type: "POST",
url: "http://your-site-url/script.php",
data: data
});
and your PHP script would look like:
// if the value was received, assign it:
if(isset($_POST['value']))
$value = $_POST['value'];
else
// do something else;

What is the most efficient and correct way of handling PHP array variables within JavaScript and being able it obtain those values using indexing

THE QUESTION
What is the most efficient and correct way of handling PHP array variables within JavaScript and being able it obtain those values using indexing.
I have a MYSQL database and have a PHP script that creates an indexed row array of the database information.
Now that this information is within the array i am comfortable about echoing this data on screen from within PHP.
i.e.
echo $lastplayed[1]['artist'];
My next step is to take the array into JavaScript so that i can use the variable information to display data on screen, make calculations and create an Ajax timer that looks for a value from a variable and refreshes the page..
Its basically a internet radio station that will display what is and has been played and when a counter reaches zero will refresh the page. (the counter being time left of a song)
I could echo each variable into a separate PHP script and then use JavaScript to call each of those PHP scripts that contain the different variables (This seems long-winded) AND puts unnecessary request strain on the MYSQL server
**I really feel that there must be a better way of transferring and handling the data, surely there must be some type of bridge between PHP and JavaScript, should i be looking into JSON ?
So my end result is to be able to take an indexed array from PHP, transfer this array into JavaScript and be able to call on different variables from within the array using indexing (i.e call the variable that resides in result 3 column 3)
And while this is happening i will be using separate PHP and JavaScript files...
Here is my code for the PHP part.
<?php
date_default_timezone_set('Europe/London');
require_once("DbConnect.php");
$sql = "SELECT `artist`, `title`, `label`, `albumyear`, `date_played`, `duration`,
`picture` FROM historylist ORDER BY `date_played` DESC LIMIT 5 ";
$result = $db->query($sql);
$lastplayed = array();
$i = 1;
while ($row=$result->fetch_object()) {
$lastplayed[$i]['artist'] = $row->artist;
$lastplayed[$i]['title'] = $row->title;
$lastplayed[$i]['label'] = $row->label;
$lastplayed[$i]['albumyear'] = $row->albumyear;
$lastplayed[$i]['date_played'] = $row->date_played;
$lastplayed[$i]['duration'] = $row->duration;
$lastplayed[$i]['picture'] = $row->picture;
$i++;
}
$starttime = strtotime($lastplayed[1]['date_played']);
$curtime = time();
$timeleft = $starttime+round($lastplayed[1]['duration']/1000)-$curtime;
$secsremain = (round($lastplayed[1]['duration'] / 1000)-($curtime-$starttime))
?>
Any thoughts on this would be greatly appreciated and thanks so much for your time.
Justin.
PROGRESS:
Thanks for the comments, i really need to take a JavaScript course at this point...
Now i have created a new output.PHP file that does the following
<?php
require_once("dblastplayedarray.php");
echo json_encode($lastplayed);
?>
So this file now echo's out the data i need in a JSON format from my array $lastplayed.
#VCNinc you say that i now can use the following code to take the data into JavaScript
<script>
var array = <?=json_encode($lastplayed)?>;
</script>
Please could you detail where i put the path information in this code so that the program knows where to look for the .PHP file output.php
Am i doing this right.. should i be printing the data into another .PHP file and then use your code to take the array into JavaScript..
Thanks
Justin.

JSON is the bridge!
You can "export" the variable to a json string and print on the output:
echo json_encode($lastplayed);
TIP: if the php file is used to show a html GUI AND you still want output a JSON too, you can create a GET variable like "&json=1" and, before output your HTML GUI, you do a IF. This way tou can use the same php file to output a GUI and the JSON. WHen you do the request via ajax, you call using the "&json=1".
if(isset($_GET['json']) && $_GET['json']==1){
echo json_encode($lastplayed);
exit;
}
Then, use AJAX to download this JSON string by calling your php script.
$.getJSON(url, function (json) {
//here the 'json' variable will be the array
//so you can interact on it if you want
$.each( json, function( key, value ) {
alert( key + ": " + value ); //here you can do anything you want
});
});

If you have a PHP array $array, you can easily export it into JavaScript like this:
<script>
var array = <?=json_encode($array)?>;
</script>
(and from that point you can manipulate it as JSON...)

How to update JavaScript variable using PHP

I have a JavaScript file named a pricing.js which contains this content in it:
var price_arr = new Array('$ 16.95','$ 30.95','$ 49.95','$ 70.95','$ 99.95','$ 109.95','$ 139.95','$ 155.95','$ 199.95','$ 460.95');
But I want to to update this part of JavaScript file using PHP so please help me in this how can I update this part of the content from JavaScript file using PHP?
'$ 16.95','$ 30.95','$ 49.95','$ 70.95','$ 99.95','$ 109.95','$ 139.95','$ 155.95','$ 199.95','$ 460.95'

Please understand that Javascript is Client Side code and PHP is server side code.
There can be 2 possible ways or scenarios which you want to achieve:
If you want to manipulate the JS file before sending it to client, you can rename the Javascript file to have .php extension and write php code to provide a variable. For Ex:
<?php
// write php code to create a string of values using a for loop
$price_array_string = "'$ 16.95','$ 30.95','$ 49.95',
'$ 70.95','$ 99.95','$ 109.95','$ 139.95','$ 155.95','$ 199.95','$ 460.95'";
// Javscript Code var price_arr = new Array(`<?`php echo $price_array_string ?>);
The other alternative is that you get the value of price array by making an Ajax Request to a PHP web service.

Simply give the pricing.js file a .php extension. You can then include PHP in the javascript file the way you would for any other page. Just be sure your HTML code specifies that it's still "text/javascript" when you load it. You'll probably want to set the content-type in the PHP file as well, like so: header("Content-type: text/javascript");

Using your PHP script you can put a value in an HTML5 data attribute of an element on your page and then read it from your JavaScript, e.g. <body data-array="'$ 16.95','$ 30.95'"> can be generated with PHP, and then read with JS: var are = new Array($('body').attr('data-array').split(',')). Here jQuery is used in order to read the attribute value, but you can also do it with pure JavaScript.