renderElement

JavaScript, Browser, Recursion

Renders the given DOM tree in the specified DOM element.

  • Destructure the first argument into type and props. Use type to determine if the given element is a text element.
  • Based on the element's type, use either Document.createTextNode() or Document.createElement() to create the DOM element.
  • Use Object.keys() to add attributes to the DOM element and set event listeners, as necessary.
  • Use recursion to render props.children, if any.
  • Finally, use Node.appendChild() to append the DOM element to the specified container.
const renderElement = ({ type, props = {} }, container) => {
  const isTextElement = !type;
  const element = isTextElement
    ? document.createTextNode('')
    : document.createElement(type);

  const isListener = p => p.startsWith('on');
  const isAttribute = p => !isListener(p) && p !== 'children';

  Object.keys(props).forEach(p => {
    if (isAttribute(p)) element[p] = props[p];
    if (!isTextElement && isListener(p))
      element.addEventListener(p.toLowerCase().slice(2), props[p]);
  });

  if (!isTextElement && props.children && props.children.length)
    props.children.forEach(childElement =>
      renderElement(childElement, element)
    );

  container.appendChild(element);
};
const myElement = {
  type: 'button',
  props: {
    type: 'button',
    className: 'btn',
    onClick: () => alert('Clicked'),
    children: [{ props: { nodeValue: 'Click me' } }]
  }
};

renderElement(myElement, document.body);

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