<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Maps</h2>
<p>Map.sizeの使用</p>
<p id="demo"></p>
<script>
// Mapを作成する
const fruits = new Map([
["apples", 500],
["bananas", 300],
["oranges", 200]
]);
document.getElementById("demo").innerHTML = fruits.size;
</script>
</body>
</html>
