How the live demo actually works.

// Nonce injected server-side so it never appears in a static file:
// var soNonce = '<?php echo wp_create_nonce("so_airtable_create"); ?>';

form.addEventListener('submit', function (e) {
    e.preventDefault();
    if ( !validateForm() ) return;
    setSubmitting(true);

    var fields = {
        'Full Name':    document.getElementById('pa-name').value.trim(),
        'Email':        document.getElementById('pa-email').value.trim(),
        'Phone Number': document.getElementById('pa-phone').value.trim(),
        'Notes':        document.getElementById('pa-notes').value.trim(),
        'Source':       'Website',   // stamped automatically — staff can filter on this
        'Status':       'New'         // default — Zapier or staff will update
    };

    var body = new FormData();
    body.append('action', 'so_airtable_create');
    body.append('nonce',  soNonce);           // WordPress nonce required by PHP handler
    body.append('table',  'Clients');
    body.append('fields', JSON.stringify(fields));

    fetch(ajaxUrl, { method: 'POST', body: body })
        .then(function (r) { return r.json(); })
        .then(function (data) {
            setSubmitting(false);
            if (data && data.success) {
                showFeedback('success', 'Submitted! Watch the live feed below.');
                form.reset();
                loadFeed();
                startPolling();   // 10-second refresh for 2 minutes
            } else {
                showFeedback('error', data.error || 'Submission failed.');
            }
        });
});

var FEED_INTERVAL = 10000;  // 10 seconds between refreshes
var FEED_DURATION = 120000; // stop after 2 minutes
var feedTimer     = null;
var feedStopTimer = null;

function loadFeed() {
    var url = ajaxUrl
        + '?action=so_airtable_proxy'
        + '&table=Clients'
        + '&sort[0][field]=Created+Time'
        + '&sort[0][direction]=desc'
        + '&maxRecords=10';

    fetch(url)
        .then(function (r) { return r.json(); })
        .then(function (data) {
            // Render records into the table — status badges colored by value
            renderFeedRows(data.records);
        });
}

function startPolling() {
    if (feedTimer) return;  // already running — do not stack intervals
    feedTimer = setInterval(loadFeed, FEED_INTERVAL);
    feedStopTimer = setTimeout(function () {
        clearInterval(feedTimer);
        feedTimer = null;
    }, FEED_DURATION);
}

loadFeed(); // always load once on page init