Adding HTML via JS

// Clear out the HTML (the same on both)
document.getElementById('demoId').innerHTML = '';

document.getElementById('demoId').innerHTML = '<div>hello world and <a>click me</a> also</div>';

// Clear out the HTML (the same on both)
document.getElementById('demoId').innerHTML = '';

var itd = document.createElement('div'),
    ita = document.createElement('a'),
    idt = document.createTextNode('hello world');
iat = document.createTextNode('click me');
idn = document.createTextNode('also');

ita.appendChild(iat);
itd.appendChild(idt);
itd.appendChild(ita);
itd.appendChild(idn)

document.getElementById('demoId').appendChild(itd);