<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
</head>
<body>
<form>
<p><input type="checkbox" id="checkId"> Are you sure?</p>
<button type="button" class="check" onclick="check()">Yes</button>
<button type="button" class="uncheck" onclick="uncheck()">No</button>
</form>
<script>
//create check function
function check() {
let inputs = document.getElementById('checkId');
inputs.checked = true;
}
//create uncheck function
function uncheck() {
let inputs = document.getElementById('checkId');
inputs.checked = false;
}
window.onload = function() {
window.addEventListener('load', check, false);
}
</script>
</body>
</html>