Run a JQuery code only for logged-in user (disable a field for logged-in user only)

add_action( 'wp_footer', function () { ?>

<script>

jQuery(document).ready(function( $ ){
    // Run this code only for logged-in user
    if(jQuery('body').hasClass('logged-in')){
        // Disable email field
        $( "#user_email_39" ).prop( "disabled", true );
        // Alert on click the email field
        $(document).on('click',function(e){
            if(e.target.id == "user_email_39"){
                alert("The input field is disabled.");
            }
        });
    }
});


</script>
<?php } );