problem in jquery ajax

I used this jquery function to send a request to abc.php; The value of x returned is correct but whatever be it value, only the if is executed; even if x is false, else 开发者_开发技巧is not executed.

$.post('abc.php',{u:e1.value},function(x){
document.getElementById('d').innerHTML+=" x="+x;
if(x){
    document.getElementById('d').style.color="green";
    document.getElementById('d').innerHTML+="<img src='t.jpeg'>";
    q=true;
    }
else{
    document.getElementById('d').style.color="red";
    document.getElementById('d').innerHTML+="U";
    q=false;
    }document.getElementById('f').innerHTML+=" q="+q;
    });
}

This is the file abc.php;

<?php
$db = "b";
$link = mysql_connect("localhost","root","");
mysql_select_db($db, $link) or die(mysql_error());
$q = "select * from us where ad='$_POST[u]'";

$r=mysql_query($q, $link) or die(mysql_error());

if(mysql_num_rows($r)==1)
echo true;
else echo false;
mysql_close($link) or die(mysql_error());
?>

The data you are checking is a string not a boolean.

You test should be: x === "true" (although you may need to account for whitespace in the output of the PHP.

I think the issue is you're echoing out the variable so the data is seen as a string therefore if it is "true" or "false" the variable is always set, meaning x is true.

Try changing your statement to if(x.toLowerCase() == "true")

You can add a further = to check it is indeed a string

The data is taken as string, not boolean. and moreover you are echoing booleans instead of strings .

http://codepad.org/KCROfdqq

<?php

echo "true";   //  output : true

echo true ;   // output : 1


?>

So try these changes :

PHP:

  echo "true" ;
 and echo "false";

Javascript:

 if(x == 'true')