/**
 * バナーオブジェクト
 */
function bunner (name, url, img) {
	this.name = name;
	this.url = url;
	this.img = img;
	this.toString = function () {
		return ('<a href="' + this.url + '" target="_blank"><img src="/elements/bnr/' + this.img + '" alt="' + this.name + '" border="0" /></a>');
	}
}

/**
 * バナー用のHTMLをアウトプット
 */
function write_bunner (bunners, bunner_max) {
	bunners.pop(); // 最後の null を削除 
	bunners = shuffle(bunners);
	bunners = bunners.splice(0,bunner_max);
	for (i = 0; i < bunners.length; i++) {
	    document.write('<div>');
	    document.write(bunners[i].toString());
	    document.write('</div>');
	}
}

/**
 * shuffle
 */
function shuffle(list) {
  var i = list.length;

  while (--i) {
    var j = Math.floor(Math.random() * (i + 1));
    if (i == j) continue;
    var k = list[i];
    list[i] = list[j];
    list[j] = k;
  }

  return list;
}

/**
 * Array.shuffle // bug
 */
Array.prototype.shuffle = function(){
	var len = this.length;
	var ary = this.concat();
	var res = [];
	while(len) res.push(ary.splice(Math.floor(Math.random()*len--),1));
	return res
}