problem in variables in jquery

Question

I don't understand why I'm not getting the message as "username already exits" if type the username which is already in database.

If the username in a server, then it is returning the value as "1" otherwise empty, and despite of successfully getting the value from the server based on username is present or not, and assigning the value to variable "x", I'm unable to get message when I pass already exist username. May I know?

$(document).ready(pageInit);
function pageInit() {
$('#1').bind('blur',go);
}
function go() {
 var value = $('#1').val();
 var x = 0;
 $.post('just.do',{username:value},function(data){
    x = data;

   }
);

 if(x) {
      $('#para').show();
      $('#para').html("Username already exits");
         return false;
  }
 else {
    $('#para').hide();
       return true;
  } 
};

EDIT: This is what I'm doing in post request in servlets:

String user1 = request.getParameter("username");  
   if(user != null) {
         String query = "Select * from users where user_name="+"\""+user+"\"";
         b = db.doExecuteQuery(stmt,query);
         if(b) {
          out.write("1");
         }

}

you should post your server side code too

Web Logic
– Web Logic

2010-05-25 12:25:14 +00:00
Commented May 25, 2010 at 12:25 — Web Logic
– Web Logic, Commented May 25, 2010 at 12:25

David Hedlund · Accepted Answer · 2010-05-25 12:26:19Z

4

Your code if(x) ... executes before the http request finishes, and as a result, x will never be set when that part of the code is reached.

You want to use callbacks:

$.post('just.do',{username:value},function(data) {
   receivedResult(data);
});

...

function receivedResult(x) {
    if(x) {
     ...
    } else {
     ... 
    }
}

answered May 25, 2010 at 12:26

David Hedlund

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Comments

Nick Craver · Accepted Answer · 2010-05-25 12:27:02Z

2

You need to rearrange your go() function a bit, like this:

function go() {
  $.post('just.do',{username: $('#1').val()},function(data){
    if(data) {
      $('#para').show();
      $('#para').html("Username already exits");
      return false;
    } else {
      $('#para').hide();
      return true;
    } 
  });
}

$.post() is an asynchronous operation, so that x=data was happening after your if(x) ran...you need to rearrange a bit so that it happens after the response comes back, e.g. running or triggered from inside the callback like I have above.

answered May 25, 2010 at 12:27

Nick Craver

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