javascript - PHP alert message -

i know first thing going has been posted hundreds of times; however, have tried different methods people have suggested still no luck... trying alert message popup if login fails reason message not want appear. here's have far:

if($conn) {     $result=sqlsrv_query($conn, "select * operator     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 working fine reason can't javascript work. ideas?

i think, problem here. redirecting page before alert message

header("location: login.php"); /* redirect browser */ 

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

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

or prompt dialog user click go next page. remove header() tho

<script type="text/javascript"> <!--    var retval = confirm("login failed! want continue ?");    if( retval == true ){       window.location.href = "login.php";       return true;    }else{       alert("user not want continue!");       return false;    } //--> </script>