<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 数字</h1>
<h2>Integer 和 BigInt</h2>
<p id="demo"></p>
<script>
let x = 9999999999999999;
let y = BigInt("9999999999999999");
document.getElementById("demo").innerHTML = x + "<br>" + y;
</script>
</body>
</html>