function appendHtml(el, str) {
var div = document.createElement('div');
div.innerHTML = str;
while (div.children.length > 0) {
el.appendChild(div.children[0]);
}
}
var html = '<h1 id="title">Some Title</h1><span style="display:inline-block; width=100px;">Some arbitrary text</span>';
appendHtml(document.body, html); // "body" has two more children - h1 and span.