我嘗試使用純 javascript Ajax將當前頁面 URL ( window.location.href)傳遞給php 變量。我究竟做錯了什么？ $_REQUEST['url']計數器.js：'use strict';let clicks = document.querySelectorAll('.Counter-trigger'); // IE8let voted = localStorage.getItem('voted');let message = document.getElementById('Counter-message');let count = document.getElementById('Counter-count');let i;let url;let post;let xhr;for (let i = 0; i < clicks.length; i++) {  clicks[i].onclick = function () {    if (voted == 'voted') {      message.innerHTML = "Sorry, ...!!";    } else {      let url = window.location.href;      let post = url; // post string      let xhr = new XMLHttpRequest();      xhr.open('POST', './lib/Counter/CounterReq.php', true);      xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');      xhr.onreadystatechange = function () {        if (xhr.readyState != 4 || xhr.status != 200) return;        console.log(xhr.responseText);        message.innerHTML = "Thanks!!";        count.innerHTML = +count.textContent+1;      };      xhr.send(post);      localStorage.setItem('rate', 'voted');      voted = 'voted';    }  }}CounterReq.php$url = $_REQUEST['url']; // posted from page$origin = $_SERVER['DOCUMENT_ROOT'].parse_url($url,PHP_URL_PATH);$file = '_Counter.txt'; // counts is saved in this document$file_path = $origin.'_Counter.txt'; // counts is saved here$count = file_get_contents($file_path);if ($count == null){$count = 0; echo $count;}$count++; // increment count by 1$handle = fopen($file_path, "w+");flock($handle,LOCK_EX); // LOCK_EX (2) exclusive locking for write accessfwrite($handle, $count);flock($handle,LOCK_UN); // LOCK_EX (3) Releases a lockfclose($handle); // close file