fastdom-sequencer

A fastdom extension that prioritises tasks and executes them in 'sequence' for the best possible render performance.

• User interactions are 'protected' from tasks that cause jank
• Animations/transitions are 'protected' from DOM measurements and mutations that cause jank
• Clean Promise based API

Usage

var sequencer = require('fastdom-sequencer')

or

<script src="node_modules/fastdom/fastdom.js"></script>
<script src="node_modules/fastdom-sequencer/fastdom-sequencer.js"></script>

API

sequencer#on()

Binds a high-priority interaction that defers any .animate() or .mutate() task that are executed elsewhere in the app. This protects any interaction related UI changes from jank.

sequencer.on(element, 'scroll', function(e) {
  sequencer.mutate(...);
});

sequencer.on(element, 'click', function(e) {
  return sequencer.animate(function() {
    element.classList.add('grow');
    return element;
  });
});

sequencer.on(element, 'click', function(e) {
  return sequencer
    .animate(() => {
      element.classList.add('grow');
      return element;
    })

    .animate(() => {
      element.classList.add('shrink');
      return element;
    })
});

sequencer.off(element, 'click', callback);

• .animate() or .mutate() tasks inside the .interaction() callbacks are run instantly and not deferred.

sequencer#animate()

Should contain any animation/transition code and return the target element.

sequencer
  .animate(() => {
    element.style.transform = 'translateY(100%)');
    return element;
  })

  .then(() => {
    // transition/animation end
  });

• Is deferred by any incomplete .on() interactions
• Run instantly if no .on() interactions are happening
• Internally run inside sequencer.mutate() as DOM changes will be required to trigger animation

sequencer#mutate()

Should contain any code that is likely to cause document reflow/layout.

sequencer.mutate(() => {
  var li = document.createElement('li');
  list.appendChild(li);
});

• Is deferred by any incomplete .interactions()
• Run instantly if no .interactions() are happening
• Internally run inside sequencer.mutate() as DOM changes will be required to trigger animation

Chaining

Tasks can be chained together so that they happen sequentially.

sequencer
  .measure(() => list.clientHeight)
  .mutate(height => list.appendChild(item))
  .animate(() => {
    item.classList.add('reveal');
    return item;
  })

  .then(() => {
    console.log('all done!');
  });