iter-tools-es/impls/$distinct/async-distinct.js

The iterable toolbox

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

async function* __asyncDistinct(source, selector) {
  const set = new Set();

  for await (const value of source) {
    const key = selector ? selector(value) : value;

    if (set.has(key)) {
      continue;
    }

    set.add(key);
    yield value;
  }
}

exports.__asyncDistinct = __asyncDistinct;
const asyncDistinct = asyncIterableCurry(__asyncDistinct, {
  minArgs: 0,
  maxArgs: 1
});
exports.asyncDistinct = asyncDistinct;