How to work with a database in JS + PHP?

Question

PHP

In a program that is written in JS, subject to the conditions, there should be a record in the mysql database, I want to use php to work with the database, how to implement such a design?
if ( a == b ){ // This is JS
<?php
//Here will work with the database on php
?>
}
// Then again JS

Answer 1

$.ajax({
  url: "index.php", 
  context: $( ".myClass" ), 
  success: function(){ 
    alert('ok');
  }
});

And on the server side, you route index.php and do what you need

Answer 2

In such cases, use AJAX.

Answer 3

if ( a == b ){
//ajax request to the server script in php => the script does something (for example, works with the database) and returns the response to the client.
}