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Difference between registering a component locally and globally

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This article explores the contrast between locally and globally registering components in React JS, highlighting the distinction in component scope and usage within the application.

1 . Registering a component locally:

In ReactJS, a local component is confined to the same file or component, accessible only within its registered scope. This approach is beneficial for crafting reusable UI elements tailored to specific sections 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 

2. Registering a component Globally:

In ReactJS, a global component is one defined and accessible across various files or components, allowing shared usage throughout the entire application for enhanced reusability. This facilitates the creation of components that serve common purposes in different parts of your app.

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: 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.

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

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


Last Updated : 14 Dec, 2023
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