How to add Name to Post Submit message

To add Name to Post Submit Message, like this.

First, make sure you added Name field. Something like this

Next, use this code to Page Header Injection

<script>
window.addEventListener("load", function() {
    const form = document.querySelector('.react-form-contents');
    const submitButton = document.querySelector('.form-submit-button');
    
    function updateThankYouMessage() {
        const firstNameInput = document.querySelector('.first-name input');
        
        setTimeout(function() {
            const thankYouElements = document.querySelectorAll('.form-submission-text p');
            
            if (firstNameInput && thankYouElements.length > 0) {
                const firstName = firstNameInput.value.trim();
                if (firstName) {
                    thankYouElements.forEach(element => {
                        if (element.textContent === 'Thank you!') {
                            element.textContent = `Thank you @${firstName}`;
                        }
                    });
                }
            }
        }, 100);
    }
    
    if (form && submitButton) {
        form.addEventListener('submit', function(e) {
            setTimeout(updateThankYouMessage, 500);
        });
        
        submitButton.addEventListener('click', function(e) {
            if (form.checkValidity()) {
                setTimeout(updateThankYouMessage, 500);
            }
        });
    }
    
    const observer = new MutationObserver(function(mutations) {
        mutations.forEach(function(mutation) {
            if (mutation.addedNodes.length) {
                mutation.addedNodes.forEach(function(node) {
                    if (node.nodeType === 1) {
                        if ((node.classList && node.classList.contains('form-submission-text')) ||
                            node.querySelector && node.querySelector('.form-submission-text')) {
                            updateThankYouMessage();
                        }
                    }
                });
            }
        });
    });
    
    observer.observe(document.body, {
        childList: true,
        subtree: true
    });
});
</script>