<input type="button" onclick="dice()" value="Start">

function dice(){
var die1 = Math.floor(Math.random()*6 + 1),
    die2 = Math.floor(Math.random()*6 + 1),
    var score;
if (die1===1 || die2===1) {
    score=0;
} else if (die1===die2) {
    score=(die1+die2)*2;
} else {
    score=die1+die2;
}
alert("You rolled a "+die1+" and a "+die2+" for a score of "+score);
}