iter-tools-es/impls/$find-best-or/async-find-best-or.js

The iterable toolbox

const {
  asyncIterableCurry
} = require('../../internal/async-iterable.js');

const {
  __asyncPeekerate
} = require('../$peekerate/async-peekerate.js');

async function __asyncFindBestOr(iterable, notFoundValue, comparer, mapper = value => value) {
  const peekr = await __asyncPeekerate(iterable);

  if (peekr.done) {
    return notFoundValue;
  } else {
    let best = peekr.value;
    let bestValue = await mapper(best, peekr.index);
    await peekr.advance();

    while (!peekr.done) {
      const candidate = peekr.value;
      const candidateValue = await mapper(candidate, peekr.index);

      if (comparer(bestValue, candidateValue)) {
        best = candidate;
        bestValue = candidateValue;
      }

      await peekr.advance();
    }

    return best;
  }
}

exports.__asyncFindBestOr = __asyncFindBestOr;
const asyncFindBestOr = asyncIterableCurry(__asyncFindBestOr, {
  reduces: true,
  minArgs: 2,
  maxArgs: 3,
  growRight: true
});
exports.asyncFindBestOr = asyncFindBestOr;