Mastering technical interviews isn't about cramming the night before—it's about building a consistent daily habit. As part of my daily 75-minute interview prep routine, I break down core React concepts into concise, high-impact answers.
Here is Part 1 of the core React concepts every developer should master for technical rounds.
1. What is React?
15-Second Answer:
"React is an open-source, component-based JavaScript library used for building fast, interactive user interfaces. It uses a Virtual DOM to optimise rendering by updating only the specific parts of the real DOM that change."
Key Interview Points
- View Layer ($V$ in MVC): React only handles the UI layer, giving developers full flexibility over routing and state tools.
- Declarative UI: You describe what the UI should look like for a given state, and React handles the DOM updates.
2. Library vs. Framework
15-Second Answer:
"The core difference is Inversion of Control. A framework dictates your architecture and calls your code, whereas a library like React gives you full control—you call it only when you need it."
Quick Comparison
- Framework (e.g., Angular, Next.js): "Don't call us, we'll call you." It provides a pre-defined blueprint and architecture.
- Library (e.g., React Core): A set of specialised tools focused strictly on rendering UI.
3. Virtual DOM & Reconciliation
15-Second Answer:
"The Virtual DOM is an in-memory representation of the real DOM. When state changes, React creates a new Virtual DOM tree, compares it with the previous one using a diffing algorithm, and patches only the changed nodes in the real DOM."
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