Ajax error saat input cepat

misi gan, ane dsni iseng mau bikin web pulsa online, yg jadi kendala di saat input nomor hp cepat option produk ga tampil, tapi kalo input nomor hp lambat atau santuy gtu option produk muncul, ada yg salah ya dari kode saya, kode sendiri + referensi dri google hehhe

<input onchange="ajaxProduct(this.value)" oninput="ajaxProduct(this.value)" type="text" class="form-control" name="hp" maxlength="20" value="" autocomplete="off" required>

<select class="form-control" name="kode" id="kode" required>
<option value="" selected="">Pilih salah satu</option>
</select>

var myAjax;
function ajaxProduct(id){

    if(id.substr(0, 3)=='+62') {
      id = "0" + id.substr(3, id.length);
    }

    if(id.substr(0, 2)=='62') {
      id = "0" + id.substr(2, id.length);
    }

    if( (id.length>=4 && id.charAt(0)=='0') || (id.length>=3 && id.charAt(0)=='9') ){
      myAjax = makeAjax();
      var url="https://www.website.com/functions/inc/cekproduk.php?nomor=";
      url=url+id;
      myAjax.onreadystatechange=stateChangedProduct;
      myAjax.open("GET",url,true);
      myAjax.send(null);
      toggle(id);
    }
    else{
      document.getElementById("kode").innerHTML = "<option selected>Pilih nominal</option>";
    }
}

function makeAjax(){
    if (window.XMLHttpRequest){
    return new XMLHttpRequest();
    }
    if (window.ActiveXObject){
    return new ActiveXObject("Microsoft.XMLHTTP");
    }
    return null;
}

function stateChangedProduct(){
    var data;
    if (myAjax.readyState==4 && myAjax.status==200){
      data=myAjax.responseText;
      if(data.length>=0){
        document.getElementById("kode").innerHTML = data
      }else{
        document.getElementById("kode").value = "<option selected>Pilih nominal</option>";
      }
    }
}

di url https://www.website.com/functions/inc/cekproduk.php?nomor= itu berisi function untuk cek nomor, contoh https://www.website.com/functions/inc/cekproduk.php?nomor=082261788475 nnti menampilkan produk tel*omsel dll sesuai provider, makasih sebelumnya.