Mistake in transferring between PHP and JavaScript

Question

I have a PHP file and JavaScript file.

JavaScript transfers 3 variables into PHP file, PHP file transfers the result into JavaScript. The process is working and gives me the right result, however as a last action in JavaScript when I checking the result it is give me false instead of true. So please help me to find out what is wrong.

PHP:

if ((isset($_POST['st'])) && (!empty($_POST['st'])))
{
    $status=$_POST['st'];
    switch($status)
    {
        case '0': {

            break;
        }
        case "1": {  

            $login = $_POST['login'];
            $pas = $_POST['pas'];
            check($login,$pas);
            break;
        }
    }
exit;
}



function check ($login,$pas) {
include "php/log_bd.php";

$result = mysql_query("SELECT * FROM users WHERE Login='$login'",$db); //I know, i know, that it is dangerous in case of SQL injection, but I use it for educational example.
$row = mysql_fetch_array($result);
if (empty($row))
{
    exit('er');             
} 
if ($row['Pas']!= $pas)
{
    exit('er');
}

exit(0);
}

JavaScript:

$(document).on("click","input[name=door_open]", function () {

var login = $("input[name=login]").val();
var pas = $("input[name=pas]").val();

$.post("index.php",{ st:1, login:login , pas:pas} ,function(data)
        {

        alert (data); // I have 'er'
            if (data == 'er')
                {
                    alert ("Sorry incorrect data");
                        return false;
                }
            else 
                {alert (data);}
        });
return false;
});

So It give me in JavaScript file 'er' result but when I check data == 'er', it told me that it is false.

As was suggested I add some some log console comands

I want to know which error you are getting. `empty($row)` or `($row['Pas']!= $pas)` — akhilp2255, Nov 28 '15 at 05:49
It could be == vs ===. Look here for explanation: http://stackoverflow.com/questions/359494/does-it-matter-which-equals-operator-vs-i-use-in-JavaScript-comparisons — the happy mamba, Nov 28 '15 at 05:49
i tried the === instead of ==, but it is still the same problem/ — ZeroVash, Nov 28 '15 at 05:51
I did test and the error I get from - empty($row), and it is right because there is no data in the base. — ZeroVash, Nov 28 '15 at 05:53
Please check this.. and tell me if it works or not http://stackoverflow.com/questions/17847938/jquery-ajax-post-returns-what-type-of-data — akhilp2255, Nov 28 '15 at 05:58
tested and working. Server returns "er" `Sorry incorrect data` — manta, Nov 28 '15 at 06:01
-manta- Are you sure that you didn't add anything? because it still gave me wrong answer — ZeroVash, Nov 28 '15 at 06:02
undefined - it is what i found in cosole in result of action described in http://stackoverflow.com/questions/17847938/jquery-ajax-post-returns-what-type-of-data — ZeroVash, Nov 28 '15 at 06:06
-manta- yes 'er' is returned but when it is came to comparison it doesn't give me 'incorect data' — ZeroVash, Nov 28 '15 at 06:10
Remove the `alert` before your `if` statement. It's not needed as we already know 'er' is returned. I would do as other have said and change all `alert()` to `console.log()` for readability and flow. — manta, Nov 28 '15 at 06:15
if(data == "er") should return false according to you code. changing it to if(data != "er") will not return false — Kennedy Nyaga, Nov 28 '15 at 06:16
-kenny west- you are not right, the data = "er" , and in comparison - data=="er" must to give true not false. — ZeroVash, Nov 28 '15 at 06:21
Hi alex.. i just told to console log data. remove `$('#main')` stuffs — akhilp2255, Nov 28 '15 at 06:24
@JCOC611 no, checked that already (with the code supplied). There may be other echo's not listed. — manta, Nov 28 '15 at 06:27
@manta all echo's and exit's is listed in the code above. all functions have exits in the end that avoid any collusions with other functions. — ZeroVash, Nov 28 '15 at 06:34
Ohk.. Just trim the data and then check... `$.trim(data) == 'er'` — akhilp2255, Nov 28 '15 at 06:35
@JCOC611 with the updated image, you are in fact correct ;) there is a new line char. — manta, Nov 28 '15 at 06:35
@akhilp2255 Can you explain why he return \ner instead of er ... Just for future people who will got the same problem, and to close out the question. — ZeroVash, Nov 28 '15 at 06:38
@JCOC611 Can you explain why he return \ner instead of er ... Just for future people who will got the same problem, and to close out the question. — ZeroVash, Nov 28 '15 at 06:38
Thanks everyone who helped me to find the mistake in the code. — ZeroVash, Nov 28 '15 at 06:40
Check out the steps given in those answer: http://stackoverflow.com/a/11593384/2919789 — akhilp2255, Nov 28 '15 at 06:43

Mistake in transferring between PHP and JavaScript

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