Implement a reducer for idle, loading, success, and error request states. Ignore stale response actions whose requestId does not match the active request.
Write down the input contract and the failure cases before coding.
tests
RUNTIME OUTPUT
Ready to run the file open above against 1 test.
Runs the open file in a restricted browser worker
LEARN FROM THE SOLUTION
Why the solution works.
Request IDs give each async response an identity. Ignoring responses from older requests prevents a slow network result from overwriting a newer search or refresh, and explicit statuses keep UI rendering straightforward.
What this exercise teaches
State machines
Immutable updates
Race-condition prevention
A PRACTICAL PLAN
Work through Model async request states with intent.
Translate the contract.Turn the requirements into a short checklist before editing your-solution.js.
Use the example as evidence.Predict the result for the supplied input, then add one boundary case such as an empty value, a limit, or unexpected input.
Review the implementation.Compare your choices against solution.js only after a real attempt.
EXERCISE FAQ
Before you move on.
What does “Model async request states” teach?
This advanced JavaScript exercise focuses on State machines, Immutable updates, Race-condition prevention. Its requirements define the exact behavior to implement before you write code.
How should I validate this JavaScript solution?
Start with the displayed example input and expected output, then test a boundary case suggested by the requirements. Open your-solution.js and select Run code. The browser executes that file in an isolated worker against the visible test cases.
When should I open the reference solution?
Attempt Model async request states first. Then open the read-only solution file to compare the contract, edge-case handling, and implementation choices—not simply to copy the final code.
