What to assess in a JavaScript developer
The language's sharp edges have not gone away because an assistant writes the first draft. They have just moved from writing to reviewing.
- Async: promises, async and await, error handling and running work in parallel safely.
- Scope and closures: what a callback captures and when it goes stale.
- Equality and types: coercion, null and undefined, and copying versus mutating objects.
- The event loop: what blocks, and why a long task freezes a page or a server.
- Modules and tooling: imports, bundling and keeping dependencies under control.
- Working with AI: reading suggested code for these pitfalls before accepting it.
Screening questions for JavaScript candidates
Code questions open a workspace beside the conversation. The workspace is TypeScript on Node, which also runs plain JavaScript-style code, and the server reruns the tests on each answer.
- A loop fires off requests and the results arrive in the wrong order. How do you fix it?
- A function mutates the object it was given and breaks another part of the app. How do you find and prevent it?
- Write a debounce function and explain when you would use it.
- An assistant suggests forEach with an async callback to process a list in order. What happens?
- How do you make sure an unhandled rejection does not silently swallow an error?
The JavaScript coding round
Choose a React (Vite), Next.js, React Native (Expo) or Node.js starter project. The candidate works in a Cursor-like IDE with Monaco, a terminal, tests, completions, file-aware chat and an agent. Guarded mode limits the helper; unguarded mode gives a full assistant.
Code is tinted by who wrote it, and the server reruns the tests when the round ends.
AI-fluency signals for a JavaScript developer
| Signal | What it tells you about a JavaScript developer |
|---|---|
| Time to first prompt | Whether they read the code and tests before asking the assistant. |
| Prompt quality | Whether prompts give context and expected behaviour rather than “make it work”. |
| AI-generated share | How much of the final code came from accepted AI output. |
| Verification | Whether they ran tests or edited code within 90 seconds of accepting a suggestion. |
| Over-reliance flags | Large accepted blocks never reviewed or tested. |
| Recovery | What they did when the assistant introduced an async or mutation bug. |
From scores to a decision
Fundamentals and AI fluency are scored separately. A score that cannot cite a real turn or edit is reported as a gap. A named person signs off every round and records the outcome.
Questions
Can the AI screen ask live JavaScript coding questions?
Yes. A code workspace on Node opens when a section calls for code, and the server reruns the candidate's tests when they send an answer.
Is SynergicHire a JavaScript coding test?
It is more than a test. It reads resumes, screens every applicant with an AI interviewer, runs coding rounds with an AI assistant, and tracks every round to a signed decision.
Do candidates get help from AI?
Only as much as you allow. Guarded mode gives a limited helper; unguarded mode gives a full assistant. The server enforces the mode.
How do I see what the candidate actually wrote?
Code is tinted by authorship, and the session replays with every edit, prompt and test run.