how to dynamically change bootstrap alert test using php?

Question

HTML:

<div id="signUpError"></div>

JS:

<script type="text/javascript">
    function showSignUpError(message) {
        document.getElementById('signUpError').innerHTML="<div class='alert alert-danger'>"+message+"</div>";    
    }
</script>

PHP:

$error="this is error"

How to call showSignUpError($error)

Answer 1

Try this code:

showSignUpError(<?php echo $error; ?>);

Try that first, but it might be necessary to quote the text:

showSignUpError("<?php echo $error; ?>");

Note that this will only run once, on page load.

If you wish to call-out to the PHP code while interacting with user, then you should check out AJAX:

AJAX request callback using jQuery