CODEWITHSUNDEEP
jqueryajaxfunction
Lyan Dwi Pangestu
Lyan Dwi Pangestu

Reputation: 473

check username with bvalidator

Why the return value of my function always false

this is my function:

function checkUsername(username) {
    var ret=false;
    $.ajax({
        type: "POST",
        url: "user_validate.php",
        async: true,
        data: "username="+username,
        success: function(data){
            if(data == 0){
                ret = true;
            }else{
               ret = false;
            }
        },
        error:function() {
            alert("ERROR");
        }
    });
    return ret;
}

Is var ret doesn't set the value? Anything wrong with it..? thanks before..!

Upvotes: 0

Views: 361

Answers (3)

dtbarne
dtbarne

Reputation: 8210

You're a little confused on the scope of things here. The ajax call is asynchronous, so by the time it answers, it no longer has anything to do with the function it was called from. What you really want to do is either set up some sort of event listener or a (my preferred method) callback.

Also, do yourself a favor and use the shortened syntax $.post(): http://api.jquery.com/jQuery.post/

function checkUsername(username) {
    $.post("user_validate.php", "username=" + username, function(data) {
        if (data == 0) {
            // Update DOM or element, or whatever you want to do
        } else {
            // Handle negative result
        }
    });
}

Upvotes: 0

Guffa
Guffa

Reputation: 700562

Because the AJAX call is asynchronpous, so you return the value of ret before it's assigned.

Use a callback method to handle the result:

function checkUsername(username, callback) {
  var ret=false;
  $.ajax({
    type: "POST",
    url: "user_validate.php",
    async: true,
    data: "username="+username,
    success: function(data){
      callback(data == 0);
    },
    error:function() {
      alert("ERROR");
    }
  });
}

Usage:

checkUsername(username, function(success){
  if (success) {
    alert('User name is valid.');
  } else {
    alert('User name is not valid.');
  }
});

Upvotes: 0

mu is too short
mu is too short

Reputation: 434765

The "A" in AJAX stands for "asynchronous"

Upvotes: 2

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