Harden promise pool executor

javascriptHARDCODING

Harden promise pool executor

Hard JavaScript arena: Promises, concurrency limits, ordering, and rejection handling

XP reward

340

Coins

Target time

40m

Mission locked

Missing prerequisites: javascript-easy-promise-pool

A browser client uploads files but must not saturate the network. You are working inside a modern JavaScript application, and the arena only clears when the result is safe, deterministic, and explainable.

Learning objective

Learn to apply Promises, concurrency limits, ordering, and rejection handling in a modern JavaScript application while explaining the invariant, safety constraints, and hidden edge cases.

Mission order

An array of async task functions and a max concurrency value. Design for correctness under duplicates, missing values, and high-volume input. Submit the solution plus enough reasoning to pass hidden edge cases.

Visible checks

sample case

Expected: 2

empty input

Expected: 0

Clear requirements

Demonstrates Promises, concurrency limits, ordering, and rejection handling
Handles the visible sample and hidden edge cases
Keeps output deterministic and explainable
Avoids unsafe dynamic execution

Secure validation contract

Judge type

CODING

Complexity target

Meets expected complexity under hidden scale cases

Workspace

Code editor

locked

Clear the route first

You can read the mission brief, but the editor, hints, tests, and submit flow stay locked until progression or plan access catches up.

Enter Immersive

Test Results

Run the visible checks when your first pass is ready.

Clear Protocol

1Read the scenario and restate the expected output shape.

2Run visible checks before chasing hidden edge cases.

3Use Genie for one nudge if stuck, then explain the invariant.

4Submit only when the result is deterministic and safe.

Rewards

340

Coins

Mission Route

Previous Next

Back to catalog

Hints

Hints are metered and logged for No Hint Hero runs.

Genie Mentor Core

Hint protocol / contextual guardrails active

Progressive hints

Failed-test aware

Solution guarded

Mission: javascript-hard-promise-pool0 attempts0 failed tests0 hints used

Progressive hint depth

Genie: Genie online. I use your mission, attempts, failed tests, hints, and path context to coach the next rep without dumping answers first.

Related Missions

Harden event loop trace

HARD / 345 XP

Harden nested array transform

HARD / 350 XP

Harden fetch retry client

HARD / 355 XP

Harden safe localStorage cache

HARD / 360 XP

Stabilize promise pool executor

MEDIUM / 180 XP

javascriptHARDCODING