Kanasansoft Web Lab.

(function(){
    var addEvent=
        function(element,eventName,handler){
            if(element.addEventListener){
                element.addEventListener(eventName,handler,true);
        }else{
            element.attachEvent("on"+eventName,handler);
        }
    }

addEvent(
    window,
    "load",
    function(){
        var getLength=
            function(str){
                return str.length+str.replace(/[\x0-\xff]/g,"").length;
            }
        var sort=
            (function(getLength){
                var _getLength=getLength;
                return function(a,b){
                    return _getLength(a)-_getLength(b);
                }
            })(getLength);
        var getColsAndRows=
            function(str){
                var ary=str.
                        replace(/\r\n/ig,"\n").
                        replace(/\r/ig,"\n").
                        split("\n");
                ary.sort(sort);
                return {
                    "cols":getLength(ary[ary.length-1]),
                    "rows":ary.length
                };
            }
        var resizeTextarea=
            function(){
                var colsAndRows=getColsAndRows(this.value);
                this.setAttribute("cols",colsAndRows.cols+1);
                this.setAttribute("rows",colsAndRows.rows+1);
            }
        var resizeTextareaHandler=
            function(textarea){
                var _textarea=textarea;
                return function(){
                    resizeTextarea.call(_textarea);
                }
            }
        var addAutoResizeTextarea=
            function(textarea){
                var handler=resizeTextareaHandler(textarea);
                handler();
                addEvent(textarea,"keyup",handler);
                addEvent(textarea,"change",handler);
            }
        var addAutoResizeTextareas=
            function(){
                var textareas=
                        document.getElementsByTagName("textarea");
                for(var i=0;i<textareas.length;i++){
                    addAutoResizeTextarea(textareas[i]);
                }
            }
        addAutoResizeTextareas();
    }
);
})();