React Interview questions

⭐

• What is the difference between state and props?
• How do you update a component’s state ?
• What is the lifecycle of a component ?

⭐⭐

• What are React hooks ?

• How would you refactor this code ?

  function Form() {
  const [firstName, setFirstName] = useState('Taylor');
  const [lastName, setLastName] = useState('Swift');
  
  const [fullName, setFullName] = useState('');
  useEffect(() => {
  setFullName(firstName + ' ' + lastName);
  }, [firstName, lastName]);
  // ...
  }

• How do you handle a complex state ?

  Let’s say I have a useState which in a parent component. This state represents complex data, and multiple children components want to update that state. What to do ?

• What is “Context” ? What do you use it for ?
• What is prop drilling ?
• How do you handle code duplication in a React codebase ?

⭐⭐⭐

• What are sources of memory leaks in React ?

• How would you refactor this code ?

  function ProductPage({ product, addToCart }) {
  useEffect(() => {
  if (product.isInCart) {
    showNotification(`Added ${product.name} to the shopping cart!`);
  }
  }, [product]);
  
  function handleBuyClick() {
  addToCart(product);
  }
  
  function handleCheckoutClick() {
  addToCart(product);
  navigateTo('/checkout');
  }
  // ...
  }

https://blog.scrimba.com/react-interview-questions/ https://beta.reactjs.org/learn/you-might-not-need-an-effect