text: 
  function addLoader(){
    document.getElementById("overlay").style.display = "block";
  }
  
  function getStatistics(filename){
      $.get( "/statistic/" + filename, function( data ) {
          if(!data["error"]){
            document.getElementById("validNumber").textContent = data["validNumber"];
            document.getElementById("discardNumber").textContent = data["discardNumber"];
          }
      });
  }
  
  function validateForm(){
    let form = document.forms["save"],
        phonePrefix = form["phonePrefix"].value.split(","),
        error = false;
  
    if(phonePrefix[phonePrefix.length - 1] === ""
      || phonePrefix[phonePrefix.length - 1] === " "){
      document.getElementsByName("phonePrefix")[0].style.borderColor = "red";
      error = true;
    }else{
      document.getElementsByName("phonePrefix")[0].style.borderColor = "#ced4da";
    }
  
    if($(form["createDiscardSheet"]).val() === "on" && form["discardName"].value === ""){
      document.getElementsByName("discardName")[0].style.borderColor = "red";
      error = true;
    }else{
      document.getElementsByName("discardName")[0].style.borderColor = "#ced4da";
    }
  
    return !error;
  }
  