Why pre-screen JavaScript developers before the technical interview
Framework experience is the easiest thing to claim and the least predictive. What separates candidates is whether they understand what happens underneath: why a callback sees the wrong value, why a promise chain swallows an error, why a list of a thousand items makes the page stutter. A short screen asks them to explain a fundamental in their own words, which sorts candidates quickly.
What actually matters when screening JavaScript Developer candidates
- 01
Technical proficiency
Check fluency in modern JavaScript: closures, promises versus async/await, event loop behaviour, ES modules, plus framework depth in React, Vue or Node with TypeScript typing habits.
- 02
Systems and trade-offs
Probe architecture calls: state management choice (Redux, Zustand, context), SSR versus SPA, bundle size budgets, REST versus GraphQL, and why they rejected the alternative.
- 03
Evidence and rigour
Test how they prove code works: Jest or Vitest coverage, Playwright or Cypress suites, Lighthouse and Core Web Vitals numbers, error tracking in Sentry, staged rollouts.
- 04
Collaboration and communication
Assess pull request review habits, handoff from Figma with designers, API contract negotiation with backend teams, and how they document components in Storybook or READMEs.
Pre-screening questions to ask JavaScript Developer candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Code they maintain
3 questions01What is your experience with the main front-end frameworks?
Listen forApplications built and maintained, with the framework's rendering and state model understood.
Framework use limited to tutorials, or state management problems solved by copying patterns.
02Do you have experience running JavaScript on the server?
Listen forServer-side work with the single-threaded model understood, and blocking operations deliberately avoided.
Blocking work performed on the main loop, or the concurrency model not understood.
03Do you have experience with typed JavaScript?
Listen forTypes used to catch real errors, with a sensible view on where strictness pays for itself.
Types bypassed routinely with escape hatches, or typing treated as unnecessary overhead.
Fundamentals real
4 questions04Can you explain how closures work?
Listen forA clear explanation with an example, including a bug they have debugged caused by one.
A memorised definition with no example, or closures confused with scope generally.
05Can you explain how context binding works in this language?
Listen forThe difference between function types and call sites explained, with a real example of it biting.
Binding explained by rule of thumb, or the difference between arrow and regular functions unclear.
06Can you explain how prototypal inheritance works?
Listen forThe prototype chain explained accurately, with class syntax understood as sitting on top of it.
Inheritance explained only through class syntax, or prototype lookup not understood.
07Can you describe the difference between the equality operators?
Listen forType coercion explained with awareness of the surprising cases, and strict comparison preferred.
The difference known as a rule without understanding coercion, or coercion cases unfamiliar.
Async handled
3 questions08What is your experience with asynchronous programming?
Listen forEvent loop behaviour understood, with concurrent operations coordinated properly rather than deeply nested.
Deeply nested callbacks, or sequential awaiting where parallel execution would be correct.
09Can you explain what a promise is and how you use one?
Listen forStates and error propagation explained, with unhandled rejections treated as a real problem.
Errors swallowed silently, or rejection handling described as optional.
10How would you handle code that is running slowly?
Listen forProfiling before changing anything, with rendering and main thread work distinguished from network.
Optimisation by guesswork, or performance problems assumed to be network related.
Structured and tested
2 questions11Which testing frameworks have you used?
Listen forTests written routinely, with a view on what is worth testing and what is not.
Testing described as somebody else's job, or coverage percentage treated as the goal.
12How do you structure code to manage complexity in a large project?
Listen forBoundaries and module structure explained, with state and side effects kept controlled.
Structure copied from a template, or shared mutable state used throughout the application.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Technical proficiency
35%5Explains event loop microtasks, hydration or bundling behaviour precisely, and names framework versions and TypeScript patterns used in production code.
Systems and trade-offs
25%5Weighs render performance, bundle weight and team maintainability against each other, citing a specific decision they later revisited and why.
Evidence and rigour
25%5Quotes before and after metrics such as LCP or bundle KB, and describes tests that caught a regression before release.
Collaboration and communication
15%5Gives concrete review examples, pushes back on unclear specs early, and leaves components documented so others ship without asking them.
Framework familiarity is easy to claim; knowing why a callback sees the wrong value is not. A screen separates them.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async. Enough to test language fundamentals and asynchronous thinking before you spend engineering time on a coding exercise.
Should I screen for a specific framework?
Test the fundamentals first. A developer who understands the language learns your framework in weeks; one who only knows a framework struggles the moment behaviour is unexpected.
Evaluating answers
What is the strongest signal when screening this role?
Explaining a fundamental like closures in their own words with an example. Developers who understand it are concrete. Anyone reciting a definition has memorised interview material.
How do I judge their asynchronous thinking?
Ask how they handle a failure inside a promise chain. Real answers cover error propagation and unhandled rejections. Anyone whose answer stops at try and catch will ship silent failures.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
