javascript - PHP alert message

I know the first thing everyone is going to say is that this has been posted hundreds of times; however, I have tried all the different methods people have suggested with still no luck... I am trying to get an alert message to popup if the login fails but for some reason the message does not want to appear. Here's what I have so far:

if($conn) {
    $result=sqlsrv_query($conn, "SELECT * FROM Operator
    WHERE Username='{$_POST['login']}'");
    $pass=sqlsrv_fetch_array($result);
    if($pass["Password"] === $_POST['password']) {
        session_start();
        $_SESSION['loggedin']=true;
        header("Location: home.php");
        exit;
    }
    else {
        header("Location: login.php");
        echo '<script type="text/javascript">';
        echo 'alert("Password Invalid!")';
        echo '</script>';
    }
}
sqlsrv_close($conn);

The php is working fine but for some reason I can't get the javascript to work. Any ideas?

if($conn) {
    $result=sqlsrv_query($conn, "SELECT * FROM Operator
    WHERE Username='{$_POST['login']}'");
    $pass=sqlsrv_fetch_array($result);
    if($pass["Password"] === $_POST['password']) {
        session_start();
        $_SESSION['loggedin']=true;
        header("Location: home.php");
        exit;
    }
    else {
        header("Location: login.php");
        echo '<script type="text/javascript">';
        echo 'alert("Password Invalid!")';
        echo '</script>';
    }
}
sqlsrv_close($conn);

The php is working fine but for some reason I can't get the javascript to work. Any ideas?

Share Improve this question asked Jul 19, 2013 at 13:27 Llama 1222 gold badges2 silver badges8 bronze badges

Can you also show us the javascript that is not working? Also, open your network tab in browser dev console. Does your ajax ever goes through? – Zlatko Commented Jul 19, 2013 at 13:29
Right click and inspect your document, is the <script> tag being echoed before the <html> tag? – Patsy Issa Commented Jul 19, 2013 at 13:30
If you're setting a redirector with Location the script will never appear. – j08691 Commented Jul 19, 2013 at 13:31
@zladuric from his line header("Location: login.php"); it's obvious it's not ajax and he's redirecting – Patsy Issa Commented Jul 19, 2013 at 13:31
@zladuric There is only one part where I'm using java... I'm trying to include the javascript inside the php code. – Llama Commented Jul 19, 2013 at 13:31

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5 Answers 5

Sorted by: Reset to default 3

i think, the problem is here. you are redirecting the page before the alert message

header("Location: login.php"); /* Redirect browser */

try removing it, or make it redirect after a couple of seconds, like this

header( "refresh:5;url=login.php" ); //redirect after 5 seconds

or you prompt a dialog for the user to click to go to next page. remove the header() tho

<script type="text/javascript">
<!--
   var retVal = confirm("Login FAILED! Do you want to continue ?");
   if( retVal == true ){
      window.location.href = "login.php";
      return true;
   }else{
      alert("User does not want to continue!");
      return false;
   }
//-->
</script>

In your code header("Location: login.php"); is there before your js code so it never execute js code it redirects to login page remove it and try.

Use this code

echo '<script>';
echo 'alert("Password Invalid!");';
echo 'location.href="login.php"';
echo '</script>';

instead of

header("Location: login.php");
echo '<script type="text/javascript">';
echo 'alert("Password Invalid!");';
echo '</script>';

Thanks.

Your code that es after the header doesn't run, maybe try setting a session variable and check for that variable in login.php. You can then call the alert from there, or just show a simple message on the page.

there is a missing semicolon right behind the alert:

if($conn) {
    $result=sqlsrv_query($conn, "SELECT * FROM Operator
    WHERE Username='{$_POST['login']}'");
    $pass=sqlsrv_fetch_array($result);
    if($pass["Password"] === $_POST['password']) {
        session_start();
        $_SESSION['loggedin']=true;
        header("Location: home.php");
        exit;
    }
    else {
        header("Location: login.php");
        echo '<script type="text/javascript">';
        echo 'alert("Password Invalid!");';
        echo '</script>';
    }
}
sqlsrv_close($conn);

didnt you check the javscript console ?

EDIT: Sorry, my fault, the semicolon isnt necessary of course.

I testet your php code on my server and it works fine anyway !

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javascript - PHP alert message - Stack Overflow

5 Answers 5

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