Iterate over complex structures

async-generator-iterator.js

const master = [
  100,
  [
    200,
    210,
    220,
    230,
    [240, 241, 242, 243, 244, 245, [2450, 2451, 2452, 2454, 2454, 2455]],
    250
  ],
  300,
  400,
  [500, 510, 520, 530, 540],
  600,
  700,
  800,
  900
];

function* iterate(arr) {
  let search = yield;
  let idx;
  tree: for (let i = 0; i < arr.length; i++) {
    if (search !== undefined && idx === undefined) {
      // Once this check is completed once, it will not run again
      idx = arr.findIndex(x => x === search);
      if (idx >= 0) {
        i = idx;
        idx = undefined;
      }
    }

    if (Number.isInteger(arr[i])) {
      if (search !== undefined && search !== arr[i]) continue;
      search = yield arr[i];
      if (search !== undefined) idx = undefined; // Reset this so the check in the beggining of the loop can execute again
    } else if (Array.isArray(arr[i])) {
      const it = iterate(arr[i]);
      it.next();
      while (true) {
        const { value, done } = it.next(search);
        if (done) break;
        search = yield value;
        if (search !== undefined) {
          // Check if the inner group contains the searched element before resarting the loop
          const found = it.next(search).value;
          if (search === found) search = yield found;
          else {
            // Reset all variables to their initial state and restart the loop to do a full check
            idx = undefined;
            i = -1;
            continue tree;
          }
        }
      }
    }
  }
}

const it = iterate(master);
it.next(); // Magic! Do not touch!