| 1 | What is the single responsibility principle and how does it apply to writing React components? React › Design Patterns in React | React | Design Patterns in React | Beginner |
| 2 | What is the container and presentational component pattern in React? React › Design Patterns in React | React | Design Patterns in React | Intermediate |
| 3 | What is the compound component pattern in React, and when is it useful? React › Design Patterns in React | React | Design Patterns in React | Advanced |
| 4 | What is the provider pattern in React and how does it relate to the Context API? React › Design Patterns in React | React | Design Patterns in React | Advanced |
| 5 | What is the controlled component pattern and why is it considered a best practice for forms? React › Design Patterns in React | React | Design Patterns in React | Intermediate |
| 6 | How does the Observer pattern let objects react automatically to events occurring in another object, and where is this pattern commonly used in PHP applications? PHP › Design Patterns in PHP | PHP | Design Patterns in PHP | Intermediate |
| 7 | How do you handle pluralization correctly across different languages in an internationalized React app? React › Internationalization (i18n) in React | React | Internationalization (i18n) in React | Advanced |
| 8 | How would you implement the Observer pattern in Java, and how does it compare to using the built-in PropertyChangeSupport or a reactive streams library? Java › Design Patterns in Java | Java | Design Patterns in Java | Advanced |
| 9 | What are CSS Modules and how do they prevent class names from clashing between components? React › Styling in React (CSS Modules, Styled Components & Tailwind) | React | Styling in React (CSS Modules, Styled Components & Tailwind) | Beginner |
| 10 | What is a general guideline for choosing between plain CSS, CSS Modules, styled components, and Tailwind for a new project? React › Styling in React (CSS Modules, Styled Components & Tailwind) | React | Styling in React (CSS Modules, Styled Components & Tailwind) | Beginner |
| 11 | What is dangerouslySetInnerHTML and why does its name include the word dangerously? React › Security in React (XSS & dangerouslySetInnerHTML) | React | Security in React (XSS & dangerouslySetInnerHTML) | Intermediate |
| 12 | How does styled components let you write CSS directly inside your JavaScript files? React › Styling in React (CSS Modules, Styled Components & Tailwind) | React | Styling in React (CSS Modules, Styled Components & Tailwind) | Intermediate |
| 13 | How would you conditionally apply different CSS classes based on a component's state, such as showing an active style? React › Styling in React (CSS Modules, Styled Components & Tailwind) | React | Styling in React (CSS Modules, Styled Components & Tailwind) | Advanced |
| 14 | What is the difference between a unit test and a component test in a React app? React › Testing | React | Testing | Beginner |
| 15 | What is snapshot testing in React, and what are its benefits and drawbacks? React › Testing | React | Testing | Intermediate |
| 16 | How would you create a reusable, generic React component using TypeScript, such as a list component that works with any data type? React › TypeScript with React | React | TypeScript with React | Advanced |
| 17 | Why is using an array's index as a key generally considered a bad practice? React › Conditional Rendering & Lists (Keys) | React | Conditional Rendering & Lists (Keys) | Intermediate |
| 18 | How would you show multiple separate loading states for different sections of a page using several Suspense boundaries? React › Suspense & Concurrent Rendering | React | Suspense & Concurrent Rendering | Intermediate |
| 19 | How do you conditionally render one of several possible components cleanly, without a long chain of if statements? React › Conditional Rendering & Lists (Keys) | React | Conditional Rendering & Lists (Keys) | Advanced |
| 20 | How would you validate a form in React and show an error message to the user? React › Forms: Controlled & Uncontrolled Components | React | Forms: Controlled & Uncontrolled Components | Intermediate |
| 21 | What is a higher order component in React? React › Higher-Order Components (HOCs) | React | Higher-Order Components (HOCs) | Intermediate |
| 22 | Why should you avoid overusing useMemo and React.memo throughout an entire app? React › Performance (memo/useMemo) | React | Performance (memo/useMemo) | Intermediate |
| 23 | What are Symfony events and event listeners, and how do they let different parts of an application react to something happening without tightly coupling that logic together? PHP › Symfony Framework Essentials | PHP | Symfony Framework Essentials | Intermediate |
| 24 | What is a React Portal and why would you use one? React › Portals & Fragments | React | Portals & Fragments | Beginner |
| 25 | How do you decide which state management library, if any, is right for a specific React project? React › State Management Libraries (Redux, Zustand & Recoil) | React | State Management Libraries (Redux, Zustand & Recoil) | Beginner |
| 26 | How would you build a custom hook to make using a specific Context simpler and safer? React › Context API | React | Context API | Intermediate |
| 27 | How would you manage a multi step form's state using useReducer instead of several separate useState calls? React › useReducer & Complex State Logic | React | useReducer & Complex State Logic | Intermediate |
| 28 | How do you pass extra data along with an action when using useReducer? React › useReducer & Complex State Logic | React | useReducer & Complex State Logic | Intermediate |
| 29 | How would you build a flexible component using multiple named slots instead of a single children prop? React › Component Composition & Children Props | React | Component Composition & Children Props | Advanced |
| 30 | What are the downsides of higher order components that led many developers to prefer custom hooks instead? React › Higher-Order Components (HOCs) | React | Higher-Order Components (HOCs) | Advanced |
| 31 | How would you build a tooltip using a Portal so it always appears above everything else on the page? React › Portals & Fragments | React | Portals & Fragments | Advanced |
| 32 | How does MutationObserver let you react to DOM changes made by other code? JavaScript › DOM & Events | JavaScript | DOM & Events | Advanced |
| 33 | How is a custom hook different from a regular helper function? React › Custom Hooks | React | Custom Hooks | Beginner |
| 34 | What does it mean for state to be normalized, and why does this matter for larger apps? React › State Management | React | State Management | Intermediate |
| 35 | How would you build a reusable error boundary that lets the user retry after an error occurs? React › Error Boundaries | React | Error Boundaries | Advanced |