function Buffer(initValue) {

    this.append(initValue);

}

Buffer.prototype = {

    items: [],

    append: function(str) {

        this.items[this.items.length] = str instanceof Buffer ?       str.toString() : str;

    return this;

},

    toString: function() {

        return this.items.join("");

    }

};

a = new Buffer("one");

a.append("two");

​

console.log(a.toString());