PHP echo not showing SweetAlert2 pop-up

Question

I'm trying to output a SweetAlert2 message box when a user leaves a username/password input box empty.

if(empty($_POST["username"]) || empty($_POST["password"]))  
       {  
           echo '<script language="javascript">';
           echo 'Swal.fire({
                          type: \"error\",
                          title: \"Oops...\",
                          text: \"Please provide login credentials!\"
                          })';
           echo '</script>'; 
       }  

I've included \\ to escape quotes but no message box is appearing at all. Any ideas?

Answer 1

To avoid a lot of escaping I normally write larger HTML blocks inside of PHP like this:

<?php
if(empty($_POST["username"]) || empty($_POST["password"])) {
?>
<script>
    Swal.fire({
        type: "error",
        title: "Oops...",
        text: "Please provide login credentials!"
    });
</script>
<?php } ?>

Your code is not producing valid JavaScript because the escape \\ is not necessary and therefor will be outputted. The JavaScript engine of your browser does not know what type: \\"error\\" should be and probably you will see an error in your console.

Make sure to include SweetAlert2 BEFORE your code for showing the alert (example for using the CDN):

<script src="https://cdn.jsdelivr.net/npm/sweetalert2@9"></script>

Maybe you have this include at the bottom of your body but your condition is in the middle of your page?

EDIT: The language attribute for the HTML <script/> element is deprecated and should be ommited.