Why parameter callback from $.post isn't accurate

I create button with many task such as create info and send it via $.post method and I have to check while data is exist in my database and it's succesfull but while I click the previous parameter is still exist, how to set it to be default..

Please, I need help thanks a ton

cek_data();
if(cek == "NOK"){
    alert("Exist");
}else{
    alert("Data isn't Exist");
}

function cek_data(){
   //statement to store url and data开发者_如何学C
   $.post( url, data ,
   function(data) {
      cek= data;
   });
}

I use die("NOK") to destination PHP file... and I implement to button on click function...

While I am not too sure what you are asking I will guess. You want to call cek_data() and return a value into cek? I would just use the $.ajax call with async set to false. In the success function set cek=data. dont do cek= cek_data();, just do cek_data();

I can hardly understand your code, but I think you want something like this:

if (update === true) {
    $(".name" + id.val()).text(name.val());
    operasi_cat = "update";
    cat_id = cat_id;
    hint = "Data sudah di-Update";
    kirim();
} else {
    cek_data();
}


function cek_data() {
  //statement to store url and data
  $.post(url, data, function(data) {
     if (cek !== "NOK") {
        //statement to append data into div element
        kirim();
     } else {
       //statement to tell data is exist
     }
  });
}