App with createElement

createElement.js

const component = function(name, props, children) {
  let elem = document.createElement(name);

  Object.keys(props).forEach(key => {
    if (key === 'style') {
      Object.assign(elem.style, props[key])
    } else {
      elem.setAttribute(key, props[key]);
      // elem[key] = props[key];
    }
  });
  
  var children = Array.prototype.slice.call(arguments, 2);
  if (children && children.length > 0) {
    children.forEach(child => {
      if (typeof child === "string") {
        child = document.createTextNode(child);
      }
      elem.appendChild(child);
    });
  };

  return elem;
};


let App =
  component('div', { className: 'app' },
    component('div', { className: 'app__logo' }),
    component('span', { className: 'app__text' },
      'hello'
    )
  );

window.onload = () => {
  document.body.appendChild(App);
}