(el → dom, classid → string)
- add element has exit
function (el, classid) {
  createEl.exit = el
  var cElm_enter = createEl.$enter.length

  // remove element if has in createEl.$enter
  var i
  if (cElm_enter > 0) {
    for (i = 0;i < cElm_enter; i++) {
      if (isDefine(createEl.$enter[i]) && isDefine(createEl.$enter[i].class) && createEl.$enter[i].class === classid) {
        createEl.$enter.splice(i,1)
      }
    }
  }

  // push an element
  if (!hasObj_Array(createEl.$exits, 'class', classid).is) createEl.$exits.push({class: classid, el: el})
}