Javascript 如何获取登录id

我从mysql数据库获取数据，然后用javascript将数据写入表中，但我只想写入我登录的帐户的数据

这是我的php文件

<?php 
 require("sistem/baglan.php");

 if($_POST){
 $sahaid = $_POST["id"]

 $list = $db-> query("SELECT *
 FROM saat 
 INNER JOIN takim ON saat.takim_id = takim.id WHERE saat_durum='dolu' AND saha_id='$sahaid'")- 
 >fetchAll(PDO::FETCH_ASSOC);

 echo json_encode($list);
 }


 ?>

---

使用会话变量存储用户id。这是你应该做的最低限度。
请分享你得到的确切错误，“语法错误”可能意味着很多事情。但一定要先阅读。请注意，您编写查询的方式是不安全的，因为它是开放的。你应该切换到以防止它。
import { girisKontrolSaha } from './saha-giris.js';

window.onload = function () {

girisKontrolSaha();

var oReq = new XMLHttpRequest();
oReq.onreadystatechange = function () {
    if (oReq.readyState == XMLHttpRequest.DONE) {
        var response = oReq.response;
        response = JSON.parse(response);
        console.log(response);


            response.forEach(randevubilgi => {
            console.log(randevubilgi)
            var postNode = document.createElement('tr');
            postNode.className = "randevutablosu"

            var card =
            '<td class="saathucre">'+
            randevubilgi.saat +
            '</td>'+
            '<td class="takimadihucre">'+
            randevubilgi.takimadi +
            '</td>'+
            '<td class="kontenjanhucre">'+
            randevubilgi.takimkontejyan +
            '</td>'+
            '<td class="kurucuhucre">'+
            randevubilgi.kurucu +
            '</td>'+
            '<td class="iptal">' + '<i class="las la-trash-alt" id="iptal-button" data-saatid="' + 
            randevubilgi.saat_id + '">'+'</i>'+ '</td>'
            ;

            postNode.innerHTML = card;
            var postList = document.getElementById("randevutablosu");
            postList.appendChild(postNode);
            });


          }
       }
      oReq.open("GET", "../../backend/randevular.php");
      oReq.send();

      }

   export function girisKontrolSaha() {
     var user;
     if (localStorage.getItem("auth-saha") != null) {
    user = localStorage.getItem("auth-saha");

    console.log("Giriş yapan kullanıcı : " + user);
    console.log("Giriş yapan kullanıcı id : " + localStorage.getItem("auth-sahaid"));
    var girislinkleri = document.getElementsByClassName("giris-linkleri");
    for (var i = 0; i < girislinkleri.length; i++) {
        girislinkleri[i].style.display = 'none';
    }

    var kullanicilinkleri = document.getElementsByClassName("kullanici-linkleri");

    for (var i = 0; i < kullanicilinkleri.length; i++) {
        kullanicilinkleri[i].style.display = 'display: block !important;';
    }
} else {
    var kullanicilinkleri = document.getElementsByClassName("kullanici-linkleri");

    for (var i = 0; i < kullanicilinkleri.length; i++) {
        kullanicilinkleri[i].style.cssText = 'display:none !important;';
    }

    window.location.replace("../../index.html");
    }
   } 

 <?php 
 require("sistem/baglan.php");

 $list = $db-> query("SELECT *
 FROM saat 
 INNER JOIN takim ON saat.takim_id = takim.id WHERE saat_durum='dolu'")->fetchAll(PDO::FETCH_ASSOC);

 echo json_encode($list);

 ?> 

Uncaught SyntaxError: Unexpected token < in JSON at position 0
at JSON.parse (<anonymous>)
at XMLHttpRequest.oReq.onreadystatechange (saha-randevular.js:11)
oReq.onreadystatechange @ saha-randevular.js:11
XMLHttpRequest.send (async)
window.onload @ saha-randevular.js:45
load (async)
(anonymous) @ saha-randevular.js:3