Verifique si no se revisó Vanila JS
<input type="checkbox" id="check">
<a href="#" onclick="check()">click</a>
<button onclick="check()">button</button>
<script>
function check() {
if (document.getElementById('check').checked) {
alert("checked");
} else {
alert("Not checked.");
}
}
</script>
Amir .R