maintpl,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script>
document.addEventListener("DOMContentLoaded", function() {
let spans = document.querySelectorAll(".list li span");
for (let { previousElementSibling: input } of spans) input.checked = true;
})
</script>
</head>
<body>
<ul class="list">
<li><input type="radio" /></li>
<li><input type="radio" /></li>
<li><input type="radio" /><span></span></li>
</ul>
</body>
</html>