用ajax获取php id？

$.ajax({
            url: "salvar.php",
            type: "post",
            async: false,
            dataType : "html",
            data: {
                "feito": 1,
                "id": id,
                "html": html,
                "css": css,
                "js": js
            },
            success: function(data) {
                alert(data.id);
            }
        });

I am using the following code made in ajax to send data to the php page doing the processing along with the database.

<?php

require_once 'banco/conexao.php';

if(isset($_POST['feito'])){
    $id_setado = $_POST["id"];
    if($id_setado === ''){
        $id = base_convert(time(), 10, 36);
        $busca = mysqli_query($conn,"SELECT id FROM codigos WHERE id = '$id'");
        $buscaId = mysqli_fetch_array($busca);
        if ($buscaId == false) {
           $html = base64_encode($_POST['html']);
           $css = base64_encode($_POST['css']);
           $js = base64_encode($_POST['js']);
           $inserir = mysqli_query($conn,"INSERT INTO codigos (id,html,css,js) VALUES ('$id','$html','$css','$js')");   
        }    
    }else{
        $id = $id_setado;
        $html = base64_encode($_POST['html']);
        $css = base64_encode($_POST['css']);
        $js = base64_encode($_POST['js']);
        $atualizar = mysqli_query($conn,"UPDATE codigos SET html='$html',css='$css',js='$js' WHERE id = '$id'");
    }
}

?>

What I would like is to know how I can get the $id that receives base_convert(time(), 10, 36); in the "success" response of ajax. Specifically this data that I want. How can I get this php variable with ajax?

Use echo to get the value of $id

echo $id