Hire Pre-vetted ReactJs talents

Here are a few React-specific interview questions to assess a candidate’s familiarity with core React concepts and patterns.

Question 1: How would you create a button counter in React?

This tests basic state management. Most solutions follow a pattern like this:

View example counter solution

There can be variability in implementation, so it’s best to run it yourself and confirm the counter updates correctly.

Question 2: How would you load data from an API on the first load of a page using React?

This examines understanding of component mounting, initial render, and using useEffect for side effects.

View example data-loading snippet

In this example, the component fetches data on first render. The empty dependency array ([]) ensures the effect runs only once when the component mounts.

Question 3: How would you create a simple login form in React?

This question is intentionally open-ended. It shows how candidates structure their JSX, manage form state, and handle submission. A strong solution uses semantic form elements and degrades gracefully without JavaScript.

Question 4: How can React.memo() optimize component rendering?

This probes advanced performance optimization knowledge.

• Answer: React.memo() wraps a component and skips re-rendering if its props haven’t changed. This is useful when a parent re-renders frequently but the memoized child’s props remain constant.

Avoid blanket statements (“never use” or “always use”); React.memo() has specific scenarios where it helps.

Question 5: What are React portals for?

Portals allow React components to render children into a DOM node outside their parent hierarchy. They’re useful for things like modals, tooltips, or overlays—and should be used sparingly to avoid complicating your component tree.