How to validate jQuery/AJAX input value in external php file and return back the result?

I have a variable called captcha from input in my form.

In my javascript file I have this:

  var captcha = $("input#captcha").val();
                    $.ajax({
                            type: "GET",
                            url: "includes/process.php",
                            data: captcha,
                            success: function() {

                              alert('Captcha is OK');

                            }
                          });

In my process.php file I have this:

<?php

// Begin the session
session_start();

// To avoid case conflicts, make the input uppercase and check against the sessi开发者_StackOverflow中文版on value
// If it's correct, echo '1' as a string
if(strtoupper($_GET['captcha']) == $_SESSION['captcha_id'])
    echo 'true';
// Else echo '0' as a string
else
    echo 'false';

?>

And my problem is that it always pass as OK, no matter what I type into input. How can I e.g. sand back to my javascript containing file the value of captcha_id so I can check it e.g. using alert in javascript?

I think that my php file is wrong, because no matter what I type into my captcha (I have checked it using alert(captcha); after var captcha = $("input#captcha").val(); and it alert the correct value.

So, I assume that the success: ... part is wrong

or

the php comparison part in process.php . What does it have to return for success part of ajx to be executed?

Thanks for any advice.

SOLVED ! at least for me ;)

This is working for me :

$.ajax({
                                type: "GET",
                                url: "includes/process.php",
                                data: "captcha=" + captcha,
                                success:function(data){
                                    if(data=='true')
                                    alert("OK");

                                else
                                alert("not ok");

                                }
                          });

process.php remains untouched.

Thanks you all, you have helped me a lot.

I believe your ajax call is wrong :

data:{captcha:yourValueFromYourInput}

Then serverside you have $_GET['captcha']=yourValumeFromYourInput

The success function will be called as soon as an ajax response is available. In your case, it is either true or false. So, you should check that:

success: function(response) {
    if (response == 'true' )
        // captcha valid
    else
        alert ('wrong');
}

you are not capturing the response from the server in your success call back

success:function(data){
if(data=='true')
alert("OK");

else
alert("not ok");

}

also you may need to send the data in your ajax call as

data:{captcha:captcha},