index.html
<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF8">
<title>JavaScriptの勉強</title>
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<body>
<h1>JavaScriptの勉強</h1>
<script>
// javaScriptオブジェクト(Array)
// var a = new Array(12, 33, 55);
var a = [12, 33, 55];
console.log(a.join("|"));
console.log(a.reverse());
</script>
</body>
</html>