基于jQuery实现的设置文本区域的光标位置

$.fn.selectRange = function(start, end) {
 if(end === undefined) {
 end = start;
 }
 return this.each(function() {
 if('selectionStart' in this) {
  this.selectiOnStart= start;
  this.selectiOnEnd= end;
 } else if(this.setSelectionRange) {
  this.setSelectionRange(start, end);
 } else if(this.createTextRange) {
  var range = this.createTextRange();
  range.collapse(true);
  range.moveEnd('character', end);
  range.moveStart('character', start);
  range.select();
 }
 });
};

$.fn.setCursorPosition = function(position){
 if(this.length == 0) return this;
 return $(this).setSelection(position, position);
}

$.fn.setSelection = function(selectionStart, selectionEnd) {
 if(this.length == 0) return this;
 input = this[0];

 if (input.createTextRange) {
 var range = input.createTextRange();
 range.collapse(true);
 range.moveEnd('character', selectionEnd);
 range.moveStart('character', selectionStart);
 range.select();
 } else if (input.setSelectionRange) {
 input.focus();
 input.setSelectionRange(selectionStart, selectionEnd);
 }

 return this;
}

$.fn.focusEnd = function(){
 this.setCursorPosition(this.val().length);
  return this;
}

function setSelectionRange(input, selectionStart, selectionEnd) {
 if (input.setSelectionRange) {
 input.focus();
 input.setSelectionRange(selectionStart, selectionEnd);
 }
 else if (input.createTextRange) {
 var range = input.createTextRange();
 range.collapse(true);
 range.moveEnd('character', selectionEnd);
 range.moveStart('character', selectionStart);
 range.select();
 }
}

function setCaretToPos (input, pos) {
 setSelectionRange(input, pos, pos);
}