JS not passing vars to php?

Hi, I'm baffled here; the two following statements from my JS
file displays the correct values but the code to enter them
into a table enters zeroes. I tried document.write(s) and the
correct values were displayed.what am I missing? Thanks in advance.

var expression = value1 + op +value2 +'='+ total;
alert(expression);
<?php
include('calcbegin.html');
$servername = "localhost";
$username = "root";table
$password = "cookie";
$dbname = "homedb";
show
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error)
{ die("Connection failed: " . $conn->connect_error); }
$sql = "INSERT INTO calculator (purpose, value1, op, value2, total)
VALUES ('$purpose', '$value1', '$op', '$value2', '$total')";
if ($conn->query($sql) === TRUE)
{ echo "New record created successfully"; }
else
{ echo "Error: " . $sql . "<br>" . $conn->error; }
$conn->close();
?>

Code (markup):

 

Uhm... You can't mix js and PHP this way. PHP is run on the server, and the output is sent to the browser (or command line, or whatever you're using) - javascript run on the client (browser) and you can't use javascript variables while parsing PHP. Rethink how you're doing stuff.
You can do the complete calculations in javascript, and send the information to a background PHP-script (which can then insert it into a MySQL-table) via AJAX, for instance.

 

PoPSiCLe is right.
You can't pass js variables to php like that.

$sql = "INSERT INTO calculator (purpose, value1, op, value2, total)
VALUES ('$purpose', '$value1', '$op', '$value2', '$total')";

PHP:

$value1 from your script is undefined and it's no way equal to your value1 variable from js script.It doesn't work that way.
You can use a js ajax call that will send via post or get your js variables to a php script.
In the php script you can access those variables via $_GET or $_POST and the use them in your db insert statement.

I hope this helps.