function random_card(){
if(cards.length > 0){
var rand = Math.floor(Math.random()*cards.length);
var html = "card: <img src='./img/"+cards[rand][0]+"' /><br/>points: "+cards[rand] [1]+"<br/><br/>";
document.getElementById("myDiv").innerHTML += html;
cards.splice(rand, 1);
}
}