html.js

var html = (function(documentToBind) {
    var template = []
      , currentLevel = 0
    this.document = documentToBind || document
    function makeEleObj(tag, attributes) {
      attributes = attributes || {}
      var eleObj = {
        level: currentLevel,
        tag: tag
      }
      for(var attr in attributes) {
        if(attributes.hasOwnProperty(attr)) {
          eleObj[attr] = attributes[attr]
        }
      }
      return eleObj
    }
    function makeEle(eTemp) {
      var element = this.document.createElement(eTemp.tag)
        , excludeList = [ 'data', 'tag', 'level' ]
      if(eTemp.hasOwnProperty('data')) {
        element.dataset = {}
        for(var dataAttr in eTemp.data) {
          if(eTemp.data.hasOwnProperty(dataAttr)) {
            eTemp['data-' + dataAttr] = eTemp.data[dataAttr]
          }
        }
      }
      for(var attr in eTemp) {
        if(eTemp.hasOwnProperty(attr) && excludeList.indexOf(attr) < 0) {
          if (attr === 'text') {
            element.innerHTML = eTemp[attr]
          } else if (attr === 'className') {
            element.setAttribute('class', eTemp[attr])
          } else {
            element.setAttribute(attr, eTemp[attr])
          }
        }
      }
      return element
    }
    function addEle(tag, attributes) {
      template.push(makeEleObj(tag, attributes))
      return this
    }
    function startLevel(tag, attributes) {
      currentLevel += 1
      addEle(tag, attributes)
      return this
    }
    function endLevel() {
      currentLevel -= 1
      return this
    }
    function getLastChild(chunk) {
     var lastChildElement = chunk
     while(lastChildElement.children.length > 0) {
      lastChildElement = lastChildElement.lastChild
    }
    return lastChildElement
  }
  function appendToLast(chunk, element) {
   var lastChild = getLastChild(chunk)
   lastChild.appendChild(element)
   return chunk
  }
  function appendToLastAtLevel(chunk, level, element) {
   var selectorString = "*"
   for(var i = 0; i <= level; i++) { selectorString += ">*"; }
   var possLvls = chunk.querySelectorAll(selectorString)
   possLvls[possLvls.length - 1].parentNode.parentNode.appendChild(element)
   return chunk
  }
  function buildDOM() {
    var level = 0, chunk, element, tempLv
    chunk = makeEle(template[0])
    for(var i = 1; i < template.length; i++) {
      element = makeEle(template[i])
      tempLv = template[i].level
      if((tempLv - 1) === level) {
        chunk.appendChild(element)
      } else if(level < tempLv) {
        level += (tempLv - 1) - level
        chunk = appendToLast(chunk, element)
      } else if(level >= tempLv) {
        level -= level - (tempLv - 1)
        chunk = appendToLastAtLevel(chunk, level, element)
      }
    }
    template = []
    currentLevel = 0
    return chunk.outerHTML
  }
  return {
    add: addEle,
    and: addEle,
    contains: startLevel,
    end: endLevel,
    build: buildDOM
  }
})

//Export if possible, using underscore.js approach
if (typeof exports !== 'undefined') {
  if (typeof module !== 'undefined' && module.exports) {
    exports = module.exports = html
  }
  exports.html = html
}