Code for https://twitter.com/compooter/status/1033833990908596224

loader-helping-hand.html

<style>
* {
  font-family: -apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";
  box-sizing: border-box;
}

body {
  margin: 0px;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: 0.5s linear all;
  opacity: 1;
}

body.done {
  opacity: 0;
  top: -500px;
}

#loader {
  width: 60vw;
  border: 0.25vw solid #888;
  padding: 0.25vw;
}

#progress {
  height: 15vh;
  background-color: #32ad64;
  position: relative;
}

#handle {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: 2vw;
}

#text {
  font-weight: bold;
  font-size: 2vw;
  color: #555;
}
</style>

<div>
<div id='loader'>
  <div id='amount'>
    <div id='progress'>
      <div id='handle'></div>
    </div>
  </div>
</div>

<p id='text'><span id='complete'>0%</span> completed</p>
</div>

<script>
  const amount = document.querySelector('#amount')
  const progress = document.querySelector('#progress')
  const complete = document.querySelector('#complete')
  
  function updateProgress (percent) {
    percent = Math.max(0, Math.min(percent, 100))
    progress.style.width = percent + '%'
    complete.innerText = Math.round(percent) + '%'

    if (percent === 100) {
      document.body.classList.add('done')
    }
  }

  updateProgress(0)

  window.requestAnimationFrame(function next () {
    const width = parseFloat(progress.style.width);

    if (width > 60) {
      return;
    }

    updateProgress(width + Math.random())

    window.requestAnimationFrame(next)
  })

  const handle = document.querySelector('#handle')
  let isDragging = false
  handle.onmousedown = function () {
    isDragging = true
  }

  function getRelativeWidth (container, point) {
    const { left, right } = container.getClientRects()[0]
    const pixelWidth = Math.max(0, point.x - left)
    const fullWidth = right - left
    return 100 * (pixelWidth / fullWidth)
  }

  document.body.onmousemove = function (e) {
    if (isDragging) {
      const newWidth = getRelativeWidth(amount, e)
      updateProgress(newWidth)
    }
  }

  document.body.onmouseup = function () {
    isDragging = false
  }

</script>