Why is this function returning undefined

Asked Sep 09 '19 at 19:24

Active Sep 09 '19 at 19:24

Viewed 37 times

I've created a javascript function that calls on a php page to return either a 1 or a 0. The return is always coming back as undefined.

    $(document).ready(function(){
      if($('#username').val()!=""){
        alert(checkfees($('#username').val())); //returns undefined
        if(checkfees($('#username').val())){
          alert("has fees");
        }
        else{
          alert("no fees");
        }
      }
    });

    function checkfees(username){
      $.post( "checkfees.php", { uname: username }).done(function(data) {
        if(data=="1"){
          return true;
        }
        else{
          return false;
        }
      });
    }

The function appears to work. The variable "data" has the correct information (either a 1 or 0), so the correct if statement is hit inside the checkfees function, but the return keeps coming back as undefined.

asked Sep 09 '19 at 19:24

Edward Glasser

3

blame the "A" in "AJAX." – I wrestled a bear once. Sep 09 '19 at 19:26
Think about what functions the `return`s are actually in. – Carcigenicate Sep 09 '19 at 19:26
you are missing a return statement before `$.post`. Note that this will return a promise. Further reading in the duplicate link – messerbill Sep 09 '19 at 19:28
I thought that was what the 'done' part of the call was for. it waited until after the call finished. So i should save data as a variable and call the return outside of the post method? – Edward Glasser Sep 09 '19 at 19:29
1

by the way, `if(data=="1"){ return true; } else{ return false; }` is exactly the same thing as `return data=="1"` – I wrestled a bear once. Sep 09 '19 at 19:31
`if(checkfees($('#username').val())){` this can't work due to the async behaviour of promises. Your `.done` **will be executed** but the result will never be read due to the missing return statement – messerbill Sep 09 '19 at 19:31
Thanks, all. Got it. – Edward Glasser Sep 09 '19 at 19:51

Why is this function returning undefined

0 Answers0