React Components vs. Component Instances vs. React Elements

Question 1

What is the difference between React components, component instances, and React elements?

Answer 1

• React Components: Components are generic descriptions or blueprints for pieces of a user interface. They are written as JavaScript functions that return React elements.
• Component Instances: Component instances are the actual manifestations of components in a React application. They are created by React each time a component is used in the code and hold their own state, props, and lifecycle.
• React Elements: React elements are JavaScript objects that represent the output of using a component in the code. They contain information needed to create DOM elements for a component instance.

Question 2

How can you think of a React component in terms of its role in the user interface?

Answer 2

A React component can be thought of as a blueprint or template for a piece of the user interface. It describes how the UI should look and behave but doesn’t represent an actual instance of that UI.

Question 3

How are component instances created in React?

Answer 3

Component instances are created by React each time a component is used in the code. React calls the component function to create these instances, and each instance holds its own state, props, and lifecycle.

Question 4

What role do React elements play in the React application’s structure?

Answer 4

React elements are intermediate objects that represent the output of using a component. They contain information needed to create DOM elements for rendering, and they exist within the React application but are not the final DOM elements themselves.

Question 5

When does a React element get converted into actual DOM elements?

Answer 5

A React element gets converted into actual DOM elements during the final rendering step when React paints the elements onto the screen in the browser.