Dùng String(). String(Infinity) trả về chuỗi "Infinity".
Ví dụ
<!DOCTYPE html>
<html>
<body>
<p>Chuyển Infinity sang String</p>
<script>
var myVal = Infinity;
document.write("Chuỗi: " + String(myVal)); // "Infinity"
</script>
</body>
</html>