Ао

text[1] = '<b class="1">data1</b><br>';
document.write(text[1] );
text[2] = '<b class="2">data2</b><br>';
document.write(text[2] );
text[3] = '<b class="3">data3</b><br>;
document.write(text[3] );

var jsArr=['js1.js', 'js2.js'];
   
                    for (var jsFile in jsArr) {

                       var script = document.createElement('script');
                       script.src = "/static/js/"+jsArr[jsFile];                
                       document.body.appendChild(script[jsFile ]);
                        (function(script) {
                               return script.onload = function() {
                                    console.log(script);                              
                               };
                           })(script);
                       
                    }

<div class="countProduct">
<input class="countProduct__input" type="number" name="countProdict_id1" id="countProdict_id1" value="1">
<button type="button" onclick="quantityMinus('countProdict_id1')" class="countProduct__btn countProduct__btn--inc">
-
</button>
<button type="button" onclick="quantityPlus('countProdict_id1')" class="countProduct__btn countProduct__btn--dec">
+
</button>
</div>
                                            
<div class="countProduct">
<input class="countProduct__input" type="number" name="countProdict_id2" id="countProdict_id2" value="1">
<button type="button" onclick="quantityMinus('countProdict_id2')" class="countProduct__btn countProduct__btn--inc">
-
</button> 
<button type="button"   onclick="quantityPlus('countProdict_id2')" class="countProduct__btn countProduct__btn--dec">
+
</button>
</div>

function quantityMinus(target) {
    	let input = document.getElemetById(target);
        if (input.value > 1) {
            input.value= input.val() - 1;
        }
    }
    
    function quantityPlus(target) {
    let input = document.getElemetById(target);
        input.value = input.value + 1;
    }

<style>
            .modal.fade{
                display:none;
                position: fixed;
                top:50%;
                left:50%;
                background-color: aquamarine;
                padding: 30px;
            }
            .modal.fade.open{
                display:block;
            }
        </style>
        <div id="modal" class="modal fade">
            <div class="modal-dialog" role="document">
                <div class="modal-content tx-size-sm">
                    <div class="modal-body tx-center pd-y-20 pd-x-20">
                        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                            <span aria-hidden="true">&times;</span>
                        </button>
                        <i class="icon ion-ios-checkmark-outline tx-100 tx-success lh-1 mg-t-20 d-inline-block"></i>
                        <h4 class="tx-success tx-semibold mg-b-20">Поздравляем!</h4>
                        <p class="mg-b-20 mg-x-20"><?php echo $_SESSION['success']; unset($_SESSION['success']); ?></p>
                        <button type="button" class="btn btn-success pd-x-25" data-dismiss="modal" aria-label="Close">Продолжить</button>
                    </div>
                </div>
            </div>
        </div>
        <script  type= text/javascript>
			document.addEventListener("DOMContentLoaded", function(event) {
                    document.getElementById('modal').classList.add('open');
			});
        </script>

<form method="POST" id="fors" action="" name="formName"  >
<input type="text" name="sum" value="">
<input onclick="checkDataAjax(event)" type="button"  value="Проверить данные">
<input type="submit" id="btn" name="sum" value="Отправить" />
</form>
<div id="target"></div>

function checkDataAjax(event){
  event.preventDefault(); 
  form = new FormData(document.formName);
  let options = {
                method: "POST",               
                body:formData,
                credentials: "include",
                mode: 'cors'
            };
       let URL = "АдресВашегоСервера";
			let request = new Request(URL, options);
			
            fetch(request, options).then(function (response) {				
                return response.json();
            }).then(function (response) {
               document.getElementById('target').innerHTML = response;
            }).catch(function (error) {
              console.log(error);          
            });
  
}

<?php
$sum = $_POST["sum"];
if(!$sum)
{$sum = "Вы ничего не написали";}
echo $sum;
?>

<button class="btn-buy" onclick=cart.remove({"кроме":7})>

cart={
remove(data){
let blocks = document.getElementsByClassName("table-cart--section");
for (let block in blocks){
if (blocks[block].dataset.productid !== data["кроме"])
 blocks[block].ParrentNode.RemoveChilde(blocks[block])
}
}
}