Recuperé le GET dans l'url. dans page html

<?php

//affichage des erreurs PHP
error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);

$servername = "localhost";
$username = "redouane";
$password = "";
$dbname = "LeBabezien";
$id = !empty($_POST['id']) ? $_POST['id'] : NULL;

if(!$id){
  echo json_encode(array('ERREUR'=>'ID non envoyé !', 'POST'=>$_POST)); // Erreur corrigée ici
  exit;
}

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}


$sql = "SELECT date_article, langue, edition, src FROM article WHERE id_article='$id'";
$result = $conn->query($sql);
if(!$result){
  echo json_encode(array('ERREUR'=>$conn->error, 'POST'=>$_POST)); // Erreur corrigée icii
  exit;
}

if ($result->num_rows > 0) {
  // output data of each row
  $article_info=array();
  while ($row = $result->fetch_assoc()) {
    $article_info[] = $row;
  }
  echo json_encode($article_info);
  exit;
} else {
  echo json_encode(array('ERREUR'=>$_POST)); // Erreur corrigée ici
  exit;
}
?>

function getGET(param){
var vars = {};
	window.location.href.replace( location.hash, '' ).replace( 
		/[?&]+([^=&]+)=?([^&]*)?/gi, // regexp
		function( m, key, value ) { // callback
			vars[key] = value !== undefined ? value : '';
		}
	);

	if ( param ) {
		return vars[param] ? vars[param] : null;	
	}
	return vars;
}

  
  var id_article= getGET('id_article');

  
  console.log(id_article);
  
  
  
	$.ajax({
   url: "article_info.php",
   type: 'POST',
   dataType: 'json',
   data :{id:id_article},
   success: function(response){
        console.log("Reponse AJAX", response);

   },error:function(err){
      console.log("Erreur Ajax",err);
   }
});

$.ajax({
   url: "article_info.php",
   type: 'POST',
   dataType:'json',
   success: function(article_info) {
    
    var date=document.getElementById("date_article");
 var src=document.getElementById("img_article");
 var edition=document.getElementById("edition_article");
 
 
 date.innerHTML=article_info[0][0];
 edition.innerHTML ="Edition N°"+article_info[0][2]+" Le Babezien";

 
 src.src=article_info[0][3];
       

    },error: function(err){
      console.log('Erreur Ajax affichage',err);
     
  }

});

$.ajax({
   url: "article_info.[https://www.commentcamarche.net/php/phpintro.php3 php]",
   type: 'POST',
   dataType:'json',
   success: function(article_info) {
    
    var date=document.getElementById("date_article");
 var src=document.getElementById("img_article");
 var edition=document.getElementById("edition_article");
 
 
 date.innerHTML=article_info[0][0];
 edition.innerHTML ="Edition N°"+article_info[0][2]+" Le Babezien";

 
 src.src=article_info[0][3];

  
       

    },error: function(err){
      console.log('Erreur Ajax affichage',err);
     
  }

});