In this article, we will discuss the difference between registering a component locally and globally in ReactJS.
It refers to how you make the component available to other components in your application. Both are ways that allow us to use the same component over and over again. The main difference between the two is the scope of the component and how it can be used in your application.
1 . Registering a component locally: In ReactJS, a local component is a component that is defined and used within the same file or component. The local component is only accessible within the scope of the component it was registered in. This is useful for creating reusable UI elements that are specific to a certain part of your application.
Key Points:
- The component is only accessible within the file or component it was registered in.
- The component is not accessible to other components outside the file.
- We cannot export the Local component.
- The component is created using the function or class syntax.
Syntax: The component is created using the respective syntax.
function LocalComponent (props) {
return (
...
)
}
Parameters: It accepts the following parameters:
- props (for the functional component): An object that contains the properties passed to the component.
Example: This is a very simple and general example of local component registration. We first declare or create the component. Since it can only be used within the same file and not within the entire app, we use it directly in the same file. Also, we cannot export the Local component.
Javascript
import React from 'react' function LocalComponent(props) { return ( <div> <h1>Local Component</h1> <p>This is a local component</p> </div> ) } export default function App() { return ( <div> <LocalComponent /> </div> ) } |
Steps to run the application: Write the below code in the terminal to run the application:
npm start
Output:
Output on the browser that shows the content of local component
Explanation: First we have declared the Local component. Then we used it locally in another function named App. Here, the <LocalComponent> can be used in the App function because both the app and LocalComponent are present in the same file.
2. Registering a component Globally: In ReactJS, a global component is a component that is defined and used in different files or components. The global component can be accessed from any component in the application. This is useful for creating components that are shared across multiple parts of your application. Global components can be used throughout your entire application.
Key Points:
- The component is accessible from any component in the application.
- The component is also accessible to other components outside the file.
- The component can also be exported.
- The component is created using the function or class syntax.
- The component is registered using React.createElement method.
Syntax:
const GlobalComponent = (props) => {
return (
...
)
}
//component registering syntax
React.createElement(GlobalComponent, {...props})
Parameters:
- ReactComponent: The component class that you want to render globally ( here GlobalComponent).
- document.getElementById(‘root’): The DOM element where you want to render the component.
- props: An object that contains the properties passed to the component.
Example: Let’s declare a global component named “GlobalComponent” and use it locally but register it globally.
Javascript
import React from 'react' const GlobalComponent = (props) => { return ( <div> <h1>Global Component</h1> <p>This is a global component</p> </div> ) } export default function App() { return ( <div> {React.createElement(GlobalComponent, null)} </div> ) } |
Steps to run the application: Write the below code in the terminal to run the application:
npm start
Output:
Output on the browser that renders the content from the global component
Explanation: First we have declared the Global component. Then we used it locally in another function named App. {React.createElement(GlobalComponent, null)} –> this part of the code allows us to register the component globally. Now we can use GlobalComponent all over our app, in any file, and multiple times. For simplicity, we have used it in the same file and just registered it globally.
To register a component globally in React, you need to export it from the current file and then import it into the components where you want to use it. Globally registering a component allows you to use it in any part of your application.
Difference between Local and Global Component Registration:
|
Local Component Registration |
Global Component Registration |
|---|---|
| Only available within the component where it’s defined | Available to be used throughout the entire application |
| Useful when the component is only needed within a specific component | Useful when the component needs to be reused in multiple components |
| Avoids naming conflicts | This can lead to naming conflicts if two components have the same name |
| Improves performance | This can result in slower performance for larger applications |
| Easier maintenance | May require updates in multiple places if changes are made |
| Increases modularity and organization | This can lead to a more tightly coupled codebase |
| More straightforward debugging and testing | Can require testing the component in multiple places |
Note: The examples discussed here are simple examples, but in a more complex application, you would typically register your components locally unless they are truly shared across your entire application.
It’s important to note that when you register a component globally and you’re using it in different parts of your application, it will be re-rendered every time props are changed, also if it’s the stateful component it will have a different state for each instance.
Conclusion: In short, the choice between local and global component registration depends on the specific use case and the size and complexity of your application. You should consider the points mentioned in the table when making this decision. By understanding the differences between local and global component registration, developers can make informed decisions and build more efficient, maintainable, and scalable React applications.
