itskp-odense/Frontend/Assets/Ajax/update.js

function updatePost(id) {
    $.ajax({
        type: 'POST',
        url: '../Backend/controller/update.php',
        data: {'update_id':id},
        success:function () {
            console.log("Update was a success");
        },
        error:function (data) {
            console.log("Update was not a success");
        }
    });
}