JSFiddle - React, Tailwind, and code Playground

HTML

<div id="o" title="a" data-title="b" data-something="z"></div>

JavaScript

var el  = document.getElementById("o"),
    arr = [];
for (var i = 0, attrs = el.attributes, l=attrs.length; i < l; i++){
    if (attrs.item(i).nodeName.substr(0, 5) == 'data-') {
        arr.push(attrs.item(i).nodeName);
    }
}
$(el).text(arr.join(', '));