JavaScript 改变 H3 标签颜色 - 每秒循环切换

<!DOCTYPE html>
<html>
<head>
	<title>Change H3 Color</title>
	<style>
		h3 {
			color: black;
		}
	</style>
</head>
<body>
	<h3>Heading 1</h3>
	<h3>Heading 2</h3>
	<h3>Heading 3</h3>
	<h3>Heading 4</h3>
	<h3>Heading 5</h3>
<pre><code>&lt;script&gt;
	const headings = document.getElementsByTagName('h3');
	let index = 0;

	function changeColor() {
		headings[index].style.color = 'red';
		if (index &gt; 0) {
			headings[index-1].style.color = 'black';
		}
		index = (index + 1) % headings.length;
	}

	setInterval(changeColor, 1000);
&lt;/script&gt;
</code></pre>
</body>
</html>