Couldn't get response from database with jQuery using PHP post request - php

Question

I cannot get this script work. I try to warn if login that user entered is available. But I cannot manage this script to work:
$( "#myRegForm" ).submit(function( event ) {
var errors = false;
var userAvi = true;
var loginInput = $('#login').val();
if( loginInput == ""){
$("#errorArea").text('LOGIN CANNOT BE EMPTY!');
$("#errorArea").fadeOut('15000', function() { });
$("#errorArea").fadeIn('15000', function() { });
errors = true;
}
else if(loginInput.length < 5 ){
$("#errorArea").text('LOGIN MUST BE AT LEAST 5 CHARACTERS!');
$("#errorArea").fadeOut('15000', function() { });
$("#errorArea").fadeIn('15000', function() { });
errors = true;
}
else if (loginInput.length >=5) {
$.post('checkLogin.php', {login2: loginInput}, function(result) {
if(result == "0") {
alert("this");
}
else {
alert("that");
}
});
}
if (errors==true) {
return false;
}
});
Everything works fine until loginInput.length >=5 else block. So I assume there is a problem with getting answer from PHP file, but I cannot handle it, though I tried many different ways. Here is checkLogin.php's file (note that jQuery script and PHP file are in the same folder):
<?php
include ("bd.php");
$login2 = mysql_real_escape_string($_POST['login2']);
$result = mysql_query("SELECT login FROM users WHERE login='$login2'");
if(mysql_num_rows($result)>0){
//and we send 0 to the ajax request
echo 0;
}
else{
//else if it's not bigger then 0, then it's available '
//and we send 1 to the ajax request
echo 1;
}
?>

Answer 1

<?php
include ("bd.php");
$login2 = mysql_real_escape_string($_POST['login2']);
$result = mysql_query("SELECT login FROM users WHERE login='$login2'");
if(mysql_num_rows($result)>0){
//and we send 0 to the ajax request
echo "0"; // for you to use if(if(result == "0") you should send a string
} else {
//else if it's not bigger then 0, then it's available '
//and we send 1 to the ajax request
echo "1";
}
?>

Answer 2

You're literally sending the string 'loginInput'.
change
$.post('checkLogin.php', {login2: 'loginInput'}, function(result) {
to
$.post('checkLogin.php', {login2: loginInput}, function(result) {
Edit
I would just comment out everything except the following for now and see if that at least works
$.post('checkLogin.php', {login2: 'loginInput'}, function(result) { // put loginInput back in quotes
alert('#'+result+'#'); // # to check for whitespace
});