Kod:
<div id="warning">F12 Kullanımı Engellendi.</div>
<script>
var warning = document.getElementById("warning");
document.addEventListener("keydown", function(event) {
if (event.keyCode === 123) {
event.preventDefault();
warning.style.display = "block";
setTimeout(function() {
warning.style.display = "none";
}, 1000);
}
});
</script>
<style type="text/css">
#warning{
position: absolute;
bottom: 0;
left: 0;
align-content: center;
display: none;
background: #ef6109;
color: white ;
border-radius: 0px;
font-size: 36px;
font-family: quicksand;
padding: 8px 30px;
text-align: center;
vertical-align: middle;
margin: 20px;
}
</html>