i feel so dumb!

I wrote a code to check the uniqueness of an email and wheter it's the correct pattern.

If so, i want to display a image: 'ok'.

If not, i want to dispaly an image: 'not ok'

document.getElementById("checkemail").innerHTML = xmlhttp.responseText ;

ok, if it's unique and a correct email pattern i get as xmlhttp.responseText --> true

if not  --> false

BUTTTTTTT

this code to display not those words true of false doesnt work for some reason :s

var correct = xmlhttp.responseText;

if (correct){

document.getElementById("checkemail").innerHTML = '<img src="Images/true.gif" border="0" alt="ok" />';

}

else {

document.getElementById("checkemail").innerHTML = '<img src="Images/false.gif" border="0" alt="nok" />';

}

}

IT always displays the good image, no matter what

var correct = xmlhttp.responseText;

if (correct){

document.getElementById("checkemail").innerHTML = '<img src="Images/true.gif" border="0" alt="ok" />';

}

else {

document.getElementById("checkemail").innerHTML = '<img src="Images/false.gif" border="0" alt="nok" />';

}

}

 

IT always displays the good image, no matter what

If your 'correct' is returned as string, the if statement would always be true. Try:

if(correct == 'true') or try to handle it in a different way.

if (correct = "true") or if (correct ='true') both dont work ... OMG what's happening :S

please help... what's wrong with the syntax, why is it not interpreted well?

ok i fixed it like this, but if somebody could help clarify me for further reference it would still be very appreciated. Apparently this is not the same:

CASE 1

xmlhttp.onreadystatechange=function()
	{	
	if (xmlhttp.readyState==4)
		{	
	document.getElementById("checkemail").innerHTML = xmlhttp.responseText;			
		}	
		}

And in php script

$correct = '<img src="Images/slecht.gif" border="0" alt="ok" />'; 

$email = $_GET['email'];

if(!preg_match("/^[_\.0-9a-zA-Z-]+@([0-9a-zA-Z][0-9a-zA-Z-]+\.)+[a-zA-Z]{2,6}$/i", $email)) {
    $nietemailvorm = true;
}
else {
$nietemailvorm = false;
}

$sql = mysql_query("SELECT email FROM respondenten WHERE email= '$email' ");

if (mysql_num_rows($sql) != 0 || $nietemailvorm) {

$correct = '<img src="Images/goed.gif" border="0" alt="nok" />'; 	

}

echo $correct; 

CASE 2

var correct = xmlhttp.responseText;
	if (correct == "true"){
	document.getElementById("checkemail").innerHTML = '<img src="Images/slecht.gif" border="0" alt="ok" />'
		}
	else {
	document.getElementById("checkemail").innerHTML = '<img src="Images/goed.gif" border="0" alt="nok" />';	

$correct = 'true'; 

$email = $_GET['email'];

if(!preg_match("/^[_\.0-9a-zA-Z-]+@([0-9a-zA-Z][0-9a-zA-Z-]+\.)+[a-zA-Z]{2,6}$/i", $email)) {
    $nietemailvorm = true;
}
else {
$nietemailvorm = false;
}

$sql = mysql_query("SELECT email FROM respondenten WHERE email= '$email' ");

if (mysql_num_rows($sql) != 0 || $nietemailvorm) {

$correct = 'false'; 	

}

echo $correct; 

Both cases are technically not wrong but really depends on what your ajax request returns.

For stuff like this, you could use jQuery to handle the ajax. 100% worry free and it would look more professional too.

But still you need to be clear what you expect to receive from the ajax request.

I personally believe it is best to target the most specific element you can.  In this case all you are trying to change is the image.src attribute.  From a pure efficiency standpoint, it is much more efficient for you to return true/false than to return the html for the entire image, and to simply change the .src attribute in your javascript.