Coupon Code Field
A promo-code field that validates a code and shows feedback.
Requires Bootstrap 5. Add the CDN tags below to your page (styles in
<head>, scripts before </body>). The downloaded file already includes them.<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css"><script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js"></script><div class="card border-0 shadow-sm" style="max-width:340px"><div class="card-body">
<label class="form-label small fw-semibold">Promo code</label>
<div class="input-group"><input class="form-control" id="cpInput" placeholder="Enter code"><button class="btn btn-primary" id="cpApply">Apply</button></div>
<small class="d-block mt-2" id="cpMsg"></small>
</div></div>document.getElementById('cpApply').onclick=function(){var v=document.getElementById('cpInput').value.trim().toUpperCase(),m=document.getElementById('cpMsg');if(v==='SAVE20'){m.textContent='✓ 20% discount applied!';m.className='d-block mt-2 small text-success'}else{m.textContent='✕ Invalid or expired code.';m.className='d-block mt-2 small text-danger'}};Free to use.This component uses Bootstrap 5 (linked above). Copy any file, or download a ready-to-open .html page with the CDN links already included.