高效的Javascript 字串操作類

/**************************************************
* * 字串操作類
* * 2008-7-25
* **************************************************
* * msn:danxinju@hotmail.com
* * author:淡新舉
***************************************************/
var StringBuilder = function(){
this.arr = new Array();
};

//追加字串
StringBuilder.prototype.add = function(item){
this.arr.push(item);
};

//清Null 字元
StringBuilder.prototype.clear = function(){
this.arr.length = 0;
};

//轉換為String
StringBuilder.prototype.toString = function(){
return this.arr.join("");
};