Modal Upload
Open a modal dialog for file uploads. The uploader lives inside a centered overlay.
var modal = document.getElementById('uploadModal');
var uploader = new MultipleUpload(el, {
uploadUrl: '/api/upload'
});
openBtn.addEventListener('click', function() {
modal.style.display = 'flex';
});
closeBtn.addEventListener('click', function() {
modal.style.display = 'none';
});