<div id="form_here">
</div>
<textarea id="area"></textarea>
<script>
var form = document.createElement('form');
form.setAttribute('acton', 'http://bla.test.ru');
form.setAttribute('method', 'post');
form.setAttribute('enctype', 'multipart/form-data');
var inp = document.createElement('input');
inp.setAttribute('type', 'text');
inp.setAttribute('name', 'email');
form.appendChild( inp );
var block = document.getElementById('form_here');
block.appendChild( form );
document.getElementById('area').value = block.innerHTML;
</script>