How to use computed state in React Class Components
In React, computed state is often used to derive data from the main state. It's important to remember one constraint - direct manipulation of state is forbidden in React. You can learn more about this concept in this blog post on computed state in React.
Suppose, we have an existing state:
this.state = {
firstName: 'John',
lastName: 'Doe'
};
To compute a value based on this state, you would create a function that will be executed within the render method. You can refer to this blog post on coding standards with TypeScript to understand better coding practices.
fullName() {
return `${this.state.firstName} ${this.state.lastName}`;
}
Then call this function in your render method:
render() {
return (
<div>
<h2>{this.fullName()}</h2>
</div>
);
}
Now, the full name is dynamically calculated and will update as soon as either its first or last name changes. This article on conditional rendering with the AND operator can give further insights on dynamic rendering in React.
The use of computed state can significantly decrease complexity in your code by avoiding storing redundant data and ensuring that your data is always consistent. Remember that improperly handling computed state may result in inconsistency and subtle bugs in your application. You can refer to this blog post on using useEffect for lifecycle events to understand how to handle state changes efficiently.
References
- React: Main Concepts
- The Power of Computed Properties in JavaScript
- Understanding State and Props in React
- React Component Lifecycle
- Blog post on computed state in React
- Blog post on coding standards with TypeScript
- Article on conditional rendering with the AND operator
- Blog post on using useEffect for lifecycle events