1: Introduction of Spfx extension with Application Customizer

During creation of Spfx project via npm commands you can create:

1. WebPart
2. Extension
   
   2.1.    Application Customizers
   2.2.    Field Customizers
   2.3.    Command Sets
3. Library

1: WebPart:

Web part can be deployed on a specific page of any site collections to enhance or to develop new functionality.

2: Extension:

Extension introduced for modern SharePoint pages like to enhance or override the built in functionality of SharePoint features include notification areas, header, navigation, toolbars, list view and footer. But keep in mind using extension we are not modifying the master page just overriding the user experience.

Extensions have further 3 classifications:

2.1:      Application Customizers

2.2:      Field Customizers

2.3:      Command Sets 

2.1: Application Customizers:

Application Customizers extension is used to enhance user experience for all the pages and subsites where this extension deployed just like modified master page (But Application customizer don’t modify master page)

Don’t need to be deployed on specific page like if you want some customization should be available on all pages like master page header, navigation, footer.

Till now Microsoft introduced 2 placeholders (Header, Footer) which come along with Application Customizer by default. May be in future they will introduce more. But if you want to edit or modify UI of any other region check this:
Inject External CSS in modern UI to update navigation and top header color

We will discuss Filed Customizer and Command Sets in next blog.

Let’s create new Application Customizer Extension:

Next Steps to create Application Customizer

Thanks Best Of Luck. If you stuck somewhere please feel free to ask in Comment. #SharingIsCaring