Function mostRecent

Probably only useful on async iterators.

It will turn an async iterator into an asynchronous iterator that will always return the last known value, while waiting for the promise on the incoming iterator to resolve.

Every value on the incoming iterator will be returned at least once in order to keep the operator 'passive'. This operator will not actively drain the incoming iterator.

Example

// input iterator
const it = itr8.itr8Pushable<string>();
// output iterator that will always return the mostRecent value of the input iterator
const itOut = pipe(it, mostRecent('My initial value'));

await sleep(1);
await itOut.next(); // => { value: 'My initial value' }
await itOut.next(); // => { value: 'My initial value' }
await sleep(1);
await itOut.next(); // => { value: 'My initial value' }

it.push('2nd value');
await sleep(1);
await itOut.next(); // => { value: '2nd value' }
await itOut.next(); // => { value: '2nd value' }

it.push('third value');
// sync so 'third value' promise not resolved yet at this point
await itOut.next(); // => { value: '2nd value' }
await sleep(1);
await itOut.next(); // => { value: 'third value' }
await itOut.next(); // => { value: 'third value' }
await sleep(1);
await itOut.next(); // => { value: 'third value' }

// see evey value at least once!!!
it.push('fourth value');
it.push('fifth value');
// sync so 'third value' promise not resolved yet
await itOut.next(); // => { value: 'third value' }
await sleep(0);
await itOut.next(); // => { value: 'fourth value' }
await sleep(0);
await itOut.next(); // => { value: 'fifth value' }

it.done();
// sync so 'done' promise not resolved yet
await itOut.next(); // => { value: 'fifth value' }
await sleep(1);
await itOut.next(); // => { done: true }
await itOut.next(); // => { done: true }