Moralis with PHP only?

I’ve seen a website where they use the following links:

https://cdn.jsdelivr.net/npm/[email protected]/dist/web3.min.js
https://npmcdn.com/moralis/dist/moralis.js
…/main.js

Ok, they seem to be necessary, but in the MAIN.js file there’s this piece of code:

async function withdraw(valueWithdraw) {
const userName = user.get("username");
const toAmount = valueWithdraw;
displayMessage("00","Your transaction is being processed...");

$.post("withdraw.php", {address: userAddress, username: userName, amount: toAmount}, function(data){
if(data.match(/successfully/)){
displayMessage("00","Successful withdrawal requested");
sleep(2000).then(() => {
window.location.reload();
});
}
if(data.match(/Insufficient/)){
displayMessage("01","Insufficient funds.");
}
});

}

They make transactions using AJAX!? There’s no .SOL file, there’s no other .JS file, how is it possible to use Moralis functions with an AJAX Calls??? For every action, deposit, withdraw, purchase… There’s always an ajax call. How is that even possible?

Thanks

It could happen if the backend uses a hard coded private key to sign those transactions.