var nlelement = document.getElementById('nlwidget');
var btnbgcolour = nlelement.getAttribute('data-button-bg-color') || '';
var btnftcolour = nlelement.getAttribute('data-button-font-color') || '';
var btntohide = nlelement.getAttribute('data-hide-gen');
var btnAdjustWidth = nlelement.getAttribute('data-adjust-with');
var url = 'https://www.tennis-point.es/on/demandware.store/Sites-TPO-ES-Site/es_ES/Newsletter-ShowFormSnippet';
var iframe = document.createElement('iframe');
iframe.id = 'newsletteriframe'
iframe.setAttribute('style', 'position:relative; border:0; width:100%; height:100%; overflow:hidden;')
iframe.onload = autoResize;
iframe.src = url + '?bgc=' + btnbgcolour + '&ftc=' + btnftcolour;
if (btntohide) {
    iframe.src = iframe.src + '&bth=' + btntohide;
    if (btnAdjustWidth) {
        iframe.src = iframe.src + '&baw=' + btnAdjustWidth;
    }
}

nlelement.appendChild(iframe);

function autoResize() {
    var obj = document.getElementById('newsletteriframe');
    obj.style.height = (obj.contentWindow.document.documentElement.scrollHeight + 20) + 'px';
}
window.onresize = autoResize;