A working example of using iterators to implement a mapLimit utility function

mapLimit-example.js

async function mapLimit(array, iterateeFn, concurrency) {
  const results = [];

  async function runTasks(tasksIterator) {
    for (const [index, element] of tasksIterator) {
      console.log("Running iterateeFn for element", element);

      try {
        results[index] = await iterateeFn(element);
      } catch (error) {
        results[index] = new Error(`Failed with: ${error.message}`);
      }

      console.log("Finished for element", element);
    }
  }

  const workers = new Array(concurrency).fill(array.entries()).map(runTasks);

  await Promise.allSettled(workers);

  return results;
}

const userIds = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

async function iterateeFn(userId) {
  const response = await fetch(
    `https://jsonplaceholder.typicode.com/users/${userId}`
  );
  const user = await response.json();
  return user.name;
}

const results = await mapLimit(userIds, iterateeFn, 3);
console.log(results);

Thank you for the help, your approach is very simplistic. I eventually came up with something similar.
I appreciate your effort in helping out.
My implementation: https://codesandbox.io/s/concurrent-tasks-with-a-limit-practice-sqd1xx