Google Apps Scriptでスクレイピングをし易くするために、フロントエンドの方にお馴染みのDOM機能の一部のようなプログラムを作成。

// XmlServiceを前提としたScrapingお助けProgram

/*
* Method: getElementById
* @param {XmlService.Element} element
* @param {string} idToFind
* @return {XmlService.Element} 
* Description: if id does not exist, null will return.
*/
function getElementById(element, idToFind) { 
  var descendants = element.getDescendants();
  for (i in descendants) {
    var elmt = descendants[i].asElement();
    if (elmt != null){
      var id = elmt.getAttribute('id')
      if (id != null) {
        if (idToFind === id.getValue()){
          return elmt;
        }
      }
    }
  }
}

/*
* Method: getElementsByClassName
* @param {XmlService.Element} element
* @param {string} classToFind
* @return {Array XmlService.Element[]}
* Description: if id does not exist, empty Array will return.
*/
function getElementsByClassName(element, classToFind){
  var classes = [];
  var descendants = element.getDescendants();
  for (i in descendants) {
    var elmt = descendants[i].asElement();
    if (elmt != null){
      var class = elmt.getAttribute('class');
      if (class != null) {
        if (classToFind === class.getValue()){
          classes.push(elmt.asElement());
        }
      }
    }
  }
  return classes;
}

/*
* Method: getElementsByTagName
* @param {XmlService.Element} element
* @param {string} tagToFind
* @return {Array XmlService.Element[]}
* Description: if id does not exist, empty Array will return.
*/
function getElementsByTagName(element, tagToFind){
  var tags = []
  var descendants = element.getDescendants();
  for (i in descendants) {
    var elmt = descendants[i].asElement();
    if (elmt != null) {
      var tag = elmt.getName();
      if (tag != null) {
        if (tagToFind === tag) {
          tags.push(elmt);
        }
      }
    }
  }
  return tags;
}