a.html

<!-- code by OpenAI, Q: move focus on link by arrow key press -->
<!-- keep disclamer: You may want to modify this code to fit your specific needs, but this should give you a starting point for moving focus on arrow key press. -->

<a href="#" tabindex="1">Link 1</a>
<a href="#" tabindex="2">Link 2</a>
<a href="#" tabindex="3">Link 3</a>


<script>

// Get all of the links in the group
var links = document.querySelectorAll('a[tabindex]');


document.addEventListener('keydown', function(event) {
// Move focus to the previous element in the group
if (event.key === 'ArrowLeft') {
	// Find the currently focused link
	var currentIndex = -1;
	for (var i = 0; i < links.length; i++) {
		if (links[i] === document.activeElement) {
			currentIndex = i;
			break;
		}
	}

	// If there is a currently focused link, move focus to the previous link
	if (0 < currentIndex) {
		links[currentIndex - 1].focus();
	}
}

// Move focus to the next element in the group
if (event.key === 'ArrowRight') {
	// Find the currently focused link
	var currentIndex = -1;
	for (var i = 0; i < links.length; i++) {
		if (links[i] === document.activeElement) {
			currentIndex = i;
			break;
		}
	}

	// If there is a currently focused link, move focus to the next link
	if (-1 < currentIndex && currentIndex < links.length - 1) {
		links[currentIndex + 1].focus();
	}
}

});
</script>