function first_select(obj){
	var chks = document.getElementsByName(obj);
	for(var i=0;i<chks.length;i++){
		chks[i].checked = true;		
	}
}

function fan_select(obj){
	var chks = document.getElementsByName(obj);
	for(var i=0;i<chks.length;i++){
		if(chks[i].checked == true){
			chks[i].checked = false;
		}else{
			chks[i].checked = true;
		}
				
	}
}
function first_del(obj){
	var chks = document.getElementsByName(obj);
	for(var i=0;i<chks.length;i++){
		chks[i].checked = false;		
	}
}
function checknum(obj){
	var num = Array();
	var str = "";
	var i=0;
	var j=0;
	var k=0;
	var select = document.getElementsByName(obj);
	for(i=0;i<select.length;i++){
		if(select[i].checked == true){
			num[j] = select[i].value;
			str = num[j]+","+str;
			j++;
		}
	}
	if(str==""){
		alert('对不起没有选择歌曲');
		return false;
	}else{
		return mp3('1',str);
	}
}