Function drain

Drains the iterable of all emitted values, and then emits an empty iterable. Therefore, it cannot be used for infinite sequences.

The operator doesn't change type of the previous iterable.

import {pipe, map, wait, drain, onEnd} from 'iter-ops';

const i = pipe(
    iterable,
    map(a => myService.request(a)), // map into Promise
    wait(), // resolve each Promise
    drain(), // drain all values
    onEnd(s => {
        console.log('duration:', s.duration);
    })
);

// Below, even though we trigger iteration just for the first value,
// onEnd will still be triggerred, because we drain the iterable:

await i.first; // iterates to the first item
Copy

See

• empty
• isEmpty
• defaultEmpty