Props Validation in React — React Technical Interview Questions & Answers

Props Validation in React

Props Validation in React

  • Validation means catching wrong prop types before the UI silently breaks. New apps: TypeScript — amount: number on the component props type. Old JS apps: the prop-types package, Hello.propTypes = { name: PropTypes.string.isRequired }.
  • PropTypes usually warn in development, they don’t always crash production. Don’t treat them as security. They’re a teacher’s red pen, not a firewall.
  • Props Validation in React — output: warn: name should be string. PropTypes warn in dev. TS catches this at compile.
  Parent
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  Price → ₹199

Technical Interview Tip: TS first. PropTypes in legacy JS.

Code Examples for Props Validation in React

Example

// PropTypes
import PropTypes from "prop-types";

function Hello({ name }) {
  return <p>Hi {name}</p>;
}

Hello.propTypes = {
  name: PropTypes.string.isRequired,
};

Props Validation in React — output: warn: name should be string. PropTypes warn in dev. TS catches this at compile.

How to Explain Props Validation in React to an Interviewer

Explain Props Validation as if you are teaching a junior — definition, then one tiny UI.

TypeScript props. prop-types warnings.

What does the example show on screen (or print), and what does that prove?

Props Validation in React — output: warn: name should be string

What mistake do freshers make with Props Validation?

Thinking PropTypes secures an API.