where to put keyup event code example

Example 1: add javascript keyup on input

<input type="text" class="form-control" placeholder="Search" id="search_id"/>
<script type="text/javascript">
const log = document.getElementById('search_id');
document.addEventListener('keyup', logKey);
function logKey(e) {
	const value=log.value;
	if (e.key === 'Enter' || e.keyCode === 13) {
		transmit({search: value});
	}
};
</script>

Example 2: what is keyup and keydown

Keydown and keyup. The keydown events happens when a key is pressed down, and then keyup – when it's released