如何获取函数中父标记的属性值?

<script>
    function process(el){
        //how to retrive attr
        window.alert(el.parentNode.getAttribute('attr')); 
    }
</script>
<div attr="234234">
    <div onclick="process(this)">some content</div>
</div>

<script>
    function process(e){
        //how to retrive attr
        window.alert(e.target.parentNode.getAttribute('attr')); 
    }
</script>
<div attr="234234">
    <div onclick="process(event)">some content</div>
</div>

function process(el){
    alert($(el).parent().attr('attr'));
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div attr="234234">
    <div onclick="process(this)">some content</div>
</div>