JS获取及设置TextArea或input文本框选择文本位置的方法

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()
 }
}