getMicrodataFromElement.js

function getMicroDataFromElement(element) {
  element = element || document.body

  function descendToAttribute(scope, attribute) {
    return [].slice.apply(scope.children).reduce(function(props, child) {
      return props.concat(
        child.hasAttribute(attribute) ? [child] : descendToAttribute(child, attribute)
      )
    }, [])
  }

  function scopesUnder(scope) {
    return [].slice.apply(scope.children).reduce(function(props, child) {
      if (child.hasAttribute('itemprop')) {
        throw new Error(
          'Found itemprop="' + child.getAttribute('itemprop') + '" outside an itemscope.'
        )
      }
      return props.concat(child.hasAttribute('itemscope') ? [child] : scopesUnder(child))
    }, [])
  }

  function propsUnder(scope) {
    return descendToAttribute(scope, 'itemprop')
  }

  function dataAtScope(scope) {
    if (scope.hasAttribute('itemtype') || scope.tagName === 'TIME') return dataInPropElement(scope)
    return propsUnder(scope).reduce(function(props, element) {
      var propValue = element.hasAttribute('itemscope')
        ? dataAtScope(element)
        : dataInPropElement(element)
      props[element.getAttribute('itemprop')] = propValue
      return props
    }, {})
  }

  function dataInPropElement(element) {
    var type = element.getAttribute('itemtype')
    switch (type) {
      case 'http://schema.org/Text':
      case null:
        if (element.tagName === 'TIME') return element.getAttribute('datetime')
        if (element.tagName === 'IMG') {
          return element.getAttribute('src')
        }
        if (element.hasAttribute('content')) return element.getAttribute('content')
        return element.textContent ? element.textContent : null
      case 'http://schema.org/Integer':
      case 'http://schema.org/Number':
        return Number(element.textContent)
      case 'null':
        return null
      case 'http://schema.org/Boolean':
        return element.getAttribute('content') === 'true' || element.textContent === 'true'
      case 'http://schema.org/ItemList':
        return scopesUnder(element).map(dataAtScope)
      default:
        throw new Error(
          "Unable to parse element with itemtype '" +
            type +
            '\' (itemprop="' +
            element.getAttribute('itemprop') +
            ')"'
        )
    }
  }

  var scopes = scopesUnder(element)
  if (scopes.length !== 1)
    throw new Error('Found ' + scopes.length + ' itemscope elements in HTML:\n' + element.innerHTML)
  return dataAtScope(scopes[0])
}