action.php

<?php 
require_once 'inc/config.php';


$q = (isset($_GET['nom']))?$_GET['nom']:null;

$sql = "SELECT * FROM clients WHERE nom LIKE '%$q%'";

$res = mysqli_query($connect,$sql) or die(mysqli_error($res));

$num = mysqli_num_rows($res);
$client = [];

if ($num>0) {
   while ($data = mysqli_fetch_array($res)):

       $client[] = $data['nom'];


   endwhile;
    $clientJson = json_encode($client);
  echo $clientJson;
}




 ?>

search.js

$(document).ready(function() {
	$(document).on('keyup', 'input[name=search]', function(event) {
		event.preventDefault();

		 var data = $(this).val()

		 $.ajax({
			url:'action.php',
			type: 'GET',
			data: {nom:data},
			beforeSend:function () {
				  // $("#forms").trigger("reset");
			  // $('#btn').text('Loading ...').removeClass('btn-primary').addClass('btn-danger')
			},
			success:function(req){
				$("#result").html('')
				var reqJson = jQuery.parseJSON(req)
				for (var i = 0; i < reqJson.length; i++) {
					$("#result").append('<li>'+reqJson[i]+'</li>')	
				}
				
			
				
				console.log(jQuery.parseJSON(req));
			}
		})
		
	});
});

search.php

<?php 

include 'inc/header.php';

require_once 'inc/config.php';


 ?>



<div class="container mt-5" >
 <div class="row">
   
   <div class="col-12">
   	

   	  <div class="form-group">
   	      <input type="search" name="search" class="form-control" placeholder="Search">
   	      <ul class="list-unstyled bg-white text-success" id="result">
   	        
   	       
   	      </ul>
   	  </div>
  
   </div>

   <div class="col-12">
   	


   </div>
 </div>


</div>








 <?php 

include 'inc/footer.php';

 ?>