Fabric React's Button is a versatile component and can take many forms, which are called variants. In the earlier version of Fabric React, you could declare Button as <Button />, defining the desired buttonType to declare the variant that you want to use. But this has been deprecated and we recommend that you use a specific variant component, such as <CommandButton/>, in your definition. Using Button is a bit confusing because we already have an HTML button:
<!-- deprecated - don't use -->
<Button iconProps={ { iconName: "addFriend"} } buttonType={ButtonType.command}>Command</Button><!-- correct use of variant button -->
<CommandButton iconProps={ { iconName: "addFriend"} }>Command</CommandButton>
Currently available button types are CommandButton, CompoundButton, DefaultButton, IconButton, and PrimaryButton. To use a specific style of button, import it at the start of the web part:
import { CommandButton...
