Пожалуйста, посмотрите на этот обновленный код.Я почти уверен, что это работает.
$(".treasure").flip().find(".back").text("-")
var cardCount = 3;
var bingoCards = [];
do {
let n = Math.floor(Math.random() * 4) + 2;
if (bingoCards.indexOf(n) === -1) {
bingoCards.push(n)
let item = $(".treasure")[n-2];
$(item).find(".back").text("BINGO")
}
} while (bingoCards.length < cardCount)
$("#button").click(function() {
$("#result").html(`The numbers are: <b>${bingoCards.join(", ")}</b>`)
});
.table {
display: table;
border-collapse: separate;
/*border-spacing: 5px;*/
/*border: 1px solid #fff;*/
}
.table-row {
display: table-row;
}
.table-cell {
text-align: center;
display: table-cell;
border: 0.5px solid #231f20;
vertical-align: middle;
width: 50px;
height: 50px;
}
.treasure {
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/nnattawat/flip/master/dist/jquery.flip.min.js"></script>
<script src="https://cdn.rawgit.com/nnattawat/flip/master/dist/jquery.flip.min.js"></script>
<div class="table">
<div class="table-row">
<div class="table-cell">1</div>
<div class="table-cell treasure">
<div class="front">2</div><div class="back"></div>
</div>
<div class="table-cell treasure">
<div class="front">3</div><div class="back"></div>
</div>
<div class="table-cell treasure">
<div class="front">4</div><div class="back"></div>
</div>
<div class="table-cell treasure">
<div class="front">5</div><div class="back"></div>
</div>
<div class="table-cell">6</div>
</div>
</div>
<button id="button">Random Numbers</button>
<div id="result"></div>