firstPHP/public/js/ajax.js

function getValueSelect(){
   let selectValue = document.getElementById("selectID").value
   let request = new XMLHttpRequest();
   let button = document.getElementById("buttonAdd");
   let count = parseInt(button.dataset.count) + 1;
   button.dataset.count = count;
   console.log(count);
   request.open("GET", "/admin/set-value-select?value=" + selectValue + "&count=" + count, true)
   request.addEventListener("load", () => {
      let responseText = request.responseText;
      let targetElement = document.getElementById("buttonAdd");
      let divElement = document.createElement("div");
      divElement.innerHTML = responseText;
      targetElement.insertAdjacentElement("beforebegin", divElement);
      let deleteButton = document.getElementById("deleteButton");
      deleteButton.addEventListener("click", () => {
         divElement.remove();
      });
      divElement.appendChild(deleteButton);
   });
   request.send()
}

document.addEventListener("DOMContentLoaded", function() {

   let divElement = document.getElementsByClassName("form-block");
   let deleteButton = document.getElementsByClassName("deleteButton");
   console.log(deleteButton);
   for(let i = 0; i < deleteButton.length; i++){
      deleteButton[i].addEventListener("click", () => {
         deleteButton[i].parentElement.remove();
      });
   }

});