Function debounce

Mainly useful on async iterators (for example generated from a stream of events), but see below for other options.

Wait for x milliseconds of 'no events' before firing one. So an event will either not be handled (busy period), or handled after the calm period (so with a delay of x milliseconds)

The second parameter can be used if the timestamps can be calculated from the values on the input iterator (by default Date.now() will be used). This makes it possible to use this operator on synchronous iterators as well!

Example

// imagine a stream of values fired at this pace onto an asyncIterator called itIn:
// 1, wait 10ms, 2, 3, wait 30ms, 4, wait 10ms, 5, wait 10ms, 6, 7, 8, 9, wait 40ms, 10
const result = await pipe(itIn, debounce(20), itr8ToArray);
// => [1, 4, 10]

const valuesWithTimestamps = [
   { value: 1, timestamp: 0 },
   { value: 2, timestamp: 10 },
   { value: 3, timestamp: 10 },
   { value: 4, timestamp: 40 },
   { value: 5, timestamp: 50 },
   { value: 6, timestamp: 60 },
   { value: 7, timestamp: 60 },
   { value: 8, timestamp: 60 },
   { value: 9, timestamp: 60 },
   { value: 10, timestamp: 100 },
];

// or get the timestamp from the input values
const result = await pipe(
   itr8FromIterable(valuesWithTimestamps),
   debounce(20, ([_v, ts]) => ts),           // debounce with function that gets timestamp from input
   map(([v, _ts]) => v),                     // only keep values
   itr8ToArray,
);
// => [1, 4, 10]