1.6.0: Use microtask queue for state derivation and DOM binding

[Tao-VanJS]

Hi fellow VanJSers,

I'm happy to announce the release of VanJS 1.6.0. 🎉🎉🎉

✨ What's in the release?

In VanJS state derivation and DOM binding are done asynchronously. Previously, we're using setTimeout(updateDoms) thus the state derivation and DOM updates are scheduled in the macrotask queue. In this release, we changed it from setTimeout(updateDoms) to queueMicrotask(updateDoms) so that the state derivation and DOM updates are scheduled in the microtask queue.

We believe this change will benefit us in the following aspect:

1. Tasks in microtask queue will be executed faster. Especially, these DOM updates are guaranteed to be executed before the next browser repaint.
2. Because of the FIFO guarantee of the microtask queue, you will have better consistency guarantee of your application code. For instance, for the code below:

const a = van.state(1)
const b = van.derive(() => a.val * 2)
Promise.resolve().then(() => {
  console.log(b.val)  // guaranteed to print 2
})

2 is guaranteed to be printed. Whereas before this release, we have to wait for updateDoms to run in macrotask queue which is somewhat undeterministic.

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With this improvement, the bundle sizes increase slightly. Gzipped bundle increases to 1076 bytes (1.0kB) from 1059 bytes (1.0kB) (17 bytes increase), while minified bundle increases to 2066 bytes (2.0kB) from 2046 bytes (2.0kB) (20 bytes increase) - still being the smallest reactive UI framework in the world.

❤️ Hope you can enjoy!

Thanks @cubxx and @sirenkovladd for the ideas!