Use the onkeyup attribute. The onkeyup attribute triggers when the user releases a key.
Example
You can try to run the following code to execute a script on releasing a key −
<!DOCTYPE html>
<html>
<body>
<p>Press a key inside the textbox.</p>
<input type = "text" onkeydown = "display()">
<script>
function display() {
alert("You released a key!");
}
</script>
</body>
</html>