CSS Bootstrap creating elements via javascript
For some reason, the bootstrap classes are not getting applied to the javascript code
That because there's no function class, you should use className, check working snippet bellow.
div.className = 'form-group';
Hope this helps.
var div = document.createElement('div');
div.className = 'form-group';
var label = document.createElement('label');
label.className = 'col-sm-2 control-label';
label.innerHTML = 'Comments';
label.for = 'inputText';
var div1 = document.createElement('div');
div1.className = 'col-sm-10';
var commentText = document.createElement('textarea');
commentText.className = 'form-control';
commentText.id = 'inputText';
commentText.rows = '3';
commentText.placeholder = 'Write your comments';
div.appendChild(label);
div1.appendChild(commentText);
div.appendChild(div1);
document.body.appendChild(div);<link href="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>