文本域光标操作的jQuery扩展分享

            var field=this.get(0);
            //end未定义，则为设置光标位置
            if(arguments[1]==undefined){
                end=start;
            }
            if(document.selection){
                //IE
                var range = field.createTextRange();
                range.moveEnd(‘character’,-$(this).val().length);
                range.moveEnd(‘character’,end);
                range.moveStart(‘character’,start);
                range.select();
            }else{
                //非IE
                field.setSelectionRange(start,end);
                $(this).focus();
            }
        },
        /*
         * 选中指定字符串
         */
        iSelectStr:function(str){
            var field=this.get(0);
            var i=$(this).val().indexOf(str);
            i != -1 ? $(this).iSelectField(i,i+str.length) : false;
        },
        /*
         * 在光标之后插入字符串
         */
        iAddField:function(str){
            var field=this.get(0);
            var v=$(this).val();
            var len=$(this).val().length;
            if(document.selection){