<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
fn = function () {
alert('123');
}
</script>
</head>
<body onclick="fn()" style="width: 100vw;height: 100vh;background-color: blueviolet;">
<a href="javascript:void(0);" onclick="fn()">what</a>
</body>
</html>