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Difference Between Super and Super Props in React
When working with React class components, one often encounters the super() and super(props) calls inside the constructor. These methods are crucial for initializing a class component and inheriting properties from React.Component base class. While they may look similar at first glance, they serve different purposes depending on how you intend to use props. In this article, we'll explore the difference between super() and super(props) and help you understand when to use each.
Introduction of super() and super(props) in React
- super(): The super() function is used to call the constructor of the parent class. In React, this means calling the constructor of the React.Component base class. It is mandatory to call super() before accessing this in the constructor, as JavaScript requires subclasses to initialize their parent classes.
- super(props): When you use super(props), you not only initialize the parent class constructor but also pass the props object to it. This makes this.props available inside the constructor and enables access to props in class methods without additional bindings.
Differences Between super() and super(props)
| Aspect | super() | super(props) |
|---|---|---|
| Purpose | Calls the parent class constructor without passing any arguments. | Calls the parent class constructor and passes the props object. |
| Access to this.props in Constructor | The this.props is undefined until explicitly assigned. | The this.props is directly available inside the constructor. |
| Usage Scenario | Used when you don't need to access props the constructor. | Used when props are required in the constructor or class methods. |
| React Recommendation | Less commonly used, as most components rely on props. | Recommended for components needing props initialization. |
When to Use super() or super(props)?
- The super() is typically used in scenarios where the component doesn't require props to initialize state or handle methods. For example, a component that manages its state independently can use super().
- On the other hand, super(props) is the go-to choice when you need to access or initialize props in the constructor. This is common in components that pass down data or rely on props for functionality.
Example
Here's a quick example to illustrate the difference.
// Using super()
class MyComponent extends React.Component {
constructor() {
super();
this.state = { message: "Hello!" };
}
}
// Using super(props)
class MyComponentWithProps extends React.Component {
constructor(props) {
super(props);
this.state = { message: `Hello, ${props.name}!` };
}
}
The choice between super() and super(props) boils down to whether you need access to props in your class component. While super() is sufficient for components that don't rely on props, super(props) is essential for components that do. Understanding this distinction will help you write cleaner and more efficient React code.
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