JavaScript skill practice
How do you approach this?
Reviewing AI-Generated JavaScript Code
Published · Updated
Published by Unrust. Scoring and editorial method
Quick answer
Review AI-generated JavaScript by checking what the code will do at runtime, not only whether it parses or resembles a familiar snippet. Inspect data validation, truthiness, mutable references, promise rejection paths, and the installed API surface. Generated JavaScript can look concise while relying on a missing method, swallowing an error, or mutating an object that another caller still owns.
Original example
Question an unvalidated request body before using it
const body = JSON.parse(request.body);
const accountId = body.accountId;
await loadAccount(accountId);This original JavaScript example is deliberately small so the review questions remain visible: is request.body always a string, what happens when parsing fails, what shape does accountId require, and who handles a rejected load? The correct implementation depends on the application's request and error contract, not on a generic generated pattern.
Review runtime assumptions with concrete values
Types may be absent or broad in JavaScript, so test the values that matter: missing fields, false and zero, malformed input, and rejected promises. Check each boundary against the caller's contract instead of accepting a generic fallback that silently changes what downstream code observes.
Inspect async failure and cleanup paths
A generated happy-path await can conceal an unhandled rejection, duplicate request, stale state update, or missing cleanup action. Trace what happens when the external operation fails, resolves late, or is cancelled, then add focused evidence proportional to the consequence of getting that path wrong.
Check a concrete outcome
Use the original example with this input. These are local teaching fixtures, checked against the displayed snippet; they do not call external services.
The local stub records that unvalidated input reaches loadAccount. No real account or network is used. Parsing JSON is not validation or authorization; enforce the application's real policy at the trusted boundary.
const request = {body: '{"accountId":"outside-scope"}'};
const loaded = [];
const loadAccount = async (id) => { loaded.push(id); };| Expression after the example | Observed result |
|---|---|
| loaded | ["outside-scope"] |
Checklist
- What runtime values can cross this JavaScript boundary?
- Who owns rejected promises, cancellation, and cleanup?
- Does the installed package actually expose the imported API and signature?
Practice loop
- 01Run an AI-suggested JavaScript change with missing, falsy, and malformed inputs when they are relevant.
- 02Verify that every promise rejection and cleanup path has an intentional owner.
- 03Confirm imports and method signatures against the installed package version before merging.
Limits of this page
Runtime checks should be scaled to the risk of the change and cannot cover every browser, deployment, or dependency interaction. A single review exercise cannot establish that AI or any tool caused a result, nor can it distinguish unfamiliar project context from a durable skill issue.
Source context
Published by Unrust as practical teaching material using public language documentation and original examples. See the scoring and editorial method for scope, checking and limitations.
Check your own starting point
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