Microtasks? about native-promise-only

[getify]

Yes, you are correct, though I believe the terms (microtask, macrotask) are not fully agreed on here.

For async scheduling, NPO chooses to use setImmediate(..) if available, setTimeout(..0) otherwise. There exist several hacky ways of simulating microtask scheduling using mutation observers and other such things, but the weight of these tricks would double the size of this polyfill.

Furthermore, it is generally considered a bad practice to rely on the relative ordering of promise tasks with other async tasks. So, I don't think the "cost" of supporting something slightly more strictly adhering to the spirit of the spec is worth it in such a case. That's why NPO takes the simpler/smaller approach.