Use Builder to easily create DOM elements dynamically.


Builder.node( elementName )
Builder.node( elementName, attributes )
Builder.node( elementName, children )
Builder.node( elementName, attributes, children )
Arguments Description
elementName String, The tag name for the element
attributes Object, Typical attributes are id, className, style, onclick, etc.
children Array, List of other nodes to be appended as children

If an element of the children Array is a String or Number, it will be automatically appended as a text node. Instead of an array, children can also be a JavaScript String or Number, to ease usage.

Special cases

  • class: When specifying the class attribute for the node, use className to circumvent a Firefox bug.
  • for: To set a for attribute (in labels) use htmlFor, since ‘for’ is a reserved word in javascript.


Creating TR and TD elements

var table = Builder.node('table', {
  width: '100%',
  cellpadding: '2',
  cellspacing: '0',
  border: '0'

var tbody = Builder.node('tbody'),
    tr = Builder.node('tr', { className: 'header' }),
    td = Builder.node('td', [Builder.node('strong', 'Category')]);


You can also combine them but you need to make sure you create the tbody tag or it will not work in IE. I have tested this in FF 1.5 and IE 6. I don’t have access to other browsers. The one problem that I have found is that with TR and TD elements you can not put a style tag on them as it just makes IE stop doing the Builder Function.

Simple Example

var element = Builder.node('p', { className:'error' }, 'An error has occurred');

creates following element:

<p class="error">An error has occured</p>

Complex Example

var element = Builder.node('div', { id: 'ghosttrain' }, [
  Builder.node('div',{ className: 'controls', style: 'font-size:11px;' }, [
    Builder.node('h1', 'Ghost Train'),
    'testtext', 2, 3, 4,
    Builder.node('ul', [
      Builder.node('li', { className: 'active', onclick: 'test()' }, 'Record')

creates (without newlines):

<div id="ghosttrain">
  <div class="controls" style="font-size:11px">
    <h1>Ghost Train</h1>
      <li class="active" onclick="test()">Record</li>


In JavaScript code, if you want to use your new element, you can add it to an existing DOM element by using the browsers native appendChild function:


… or by using Protoypes built-in Element#insert method which allows you to specify a position the new node gets inserted into:

$('myExistingDomElement').insert(element); // appends the new node to @myExistingDomElement@-element
$('myExistingDomElement').insert({ after: element }); // inserts the new node right after the @myExistingDomElement@-element
$('myExistingDomElement').insert({ top: element }); // inserts the new node as the first element in @myExistingDomElement@

If you want to be able to call any of Prototype’s extension-methods on the created node, then you need to pass it through the $ function:

var div = Builder.node('div', { id: 'some_id' });
div = $(div);