vanilla js (not working in IE10 and older mostly)

vanilla-js-jquery-like-examples.js

// JSON
  const data = await (await fetch('/my-url')).json();

  // Post
  await fetch('/my-url', { method: 'POST', body: data });

  // Request
  try {
    const resp = await fetch('/my-url');
    // ...
  } catch (e) {
    // ...
  }

  // Fade In
  el.animate({ opacity: 1 }, 400);

  // Fade Out
  el.animate({ opacity: 0 }, 400);

  // Hide
  el.hidden = true;

  // Show
  el.hidden = false;

  // After
  target.after(el);

  // Append
  target.append(el);

  // Before
  target.before(el);

  // Each
  for (const el of document.querySelectorAll(selector)) {
    // ...
  }

  // Empty
  el.replaceChildren(); // or el.textContent = '', depending on which you find clearer

  // Filter
  [...document.querySelectorAll(selector)].filter(filterFn);

  // Get Height
  el.clientHeight;

  // Get Width
  el.clientWidth;

  // Matches
  el.matches('.my-class');

  // Remove
  el.remove();

  // Delegate
  document.addEventListener(eventName, e => {
    const match = e.target.closest(elementSelector);
    if (match) {
      handler.call(match, e);
    }
  });

  // Trigger Custom
  el.dispatchEvent(new CustomEvent('my-event', { detail: { some: 'data' } }));

  // Trigger Native
  el.dispatchEvent(new Event('change'));

  // Extend
  Object.assign({}, objA, objB);

  // Parse HTML
  (new DOMParser()).parseFromString(htmlString);

  // Type
  obj[Symbol.toStringTag];

as seen at https://news.ycombinator.com/item?id=25770858 (comments for You might not need jQuery (2014) (youmightnotneedjquery.com))