TextAreaの選択テキスト位置または入力テキストボックスを取得および設定するJSメソッド_javascriptスキル

function getPos(el) {
 var range, textRange, duplicate
 el.focus()
 if ( el.selectionStart ) return el.selectionStart
 else if ( document.selection ) { // IE
  range = document.selection.createRange()
  if ( range == null ) return el.value.length
  textRange = el.createTextRange()
  duplicate = textRange.duplicate()
  textRange.moveToBookmark(range.getBookmark())
  duplicate.setEndPoint('EndToStart', textRange)
  return duplicate.text.length
 }
}
function setPos(el, pos) {
 var range
 el.focus()
 if ( el.setSelectionRange )
  el.setSelectionRange(pos, pos)
 else if ( el.createTextRange ) {
  range.collapse(true)
  range.moveEnd('character', pos)
  range.moveStart('character', pos)
  range.select()
 }
}