Code example from blogpost https://medium.com/variant-as/abstracting-the-dom-by-making-ad-hoc-react-like-library-1c9b42618e63

own-ui-18.js

// Check if key starts with `on`. If so, it is an event.
const isEvent = (k, v) => k.startsWith("on") && typeof v === "function";

// Removes `on` prefix to use it as event name
const eventName = k => k.substr(2).toLowerCase();

function attrs(el, props) {
  for (let [k, val] of Object.entries(props)) {
    // Extend attribute check with special case for events
    if (isEvent(k)) {
      // Is event. Add event listener with props value as callback
      el.addEventListener(eventName(k), val);
    } else if (k === "class") {
      let classes = Array.isArray(val) ? val : [val];
      el.classList.add(...classes);
    } else {
      el.setAttribute(k, val);
    }
  }
  return el;
}