Function scheduleMicrotask

scheduleMicrotask(
callback: () => void,
options?: MicroTaskOptions,
): ITimerHandler
Schedules a callback to run in the microtask queue.

It uses the native queueMicrotask when available, otherwise falls back to Promise.resolve().then(...), and if Promise is unavailable it falls back to scheduleTimeout(..., 0). Unlike standard microtasks, this helper returns a cancellable ITimerHandler so scheduled callbacks can be canceled before execution. This provides consistent microtask scheduling behavior across all supported runtimes, including Node.js, browsers, and web workers.
Parameters
- callback: () => void
  The callback to execute.
- Optionaloptions: MicroTaskOptions
  Optional per-call fallback options when queueMicrotask is unavailable.
Returns ITimerHandler
A handler that can be used to cancel or refresh the scheduled callback.
Since
0.15.0
Example
```
let order: string[] = [];
order.push("sync");

const handler = scheduleMicrotask(() => {
    order.push("microtask");
});

scheduleTimeout(() => {
    order.push("timeout");
}, 0);

// order becomes ["sync", "microtask", "timeout"]
handler.enabled; // true until the microtask executes
```
Example
```
scheduleMicrotask(() => {
    console.log("custom fallback scheduler");
}, {
    scheduleFn: (cb) => {
        setTimeout(cb, 0);
    }
});
```
- Defined in lib/src/timer/microtask.ts:170