SlotFill

Now that the PluginDocumentSettingPanel is in WordPress core, we can add our own panels to the Document Settings panel using the registerPlugin function.

const { registerPlugin } = wp.plugins;
const { PluginDocumentSettingPanel } = wp.editPost;

const MyCustomSideBarPanel = () => (
    <PluginDocumentSettingPanel
        name="my-custom-panel"
        title="My Custom Panel"
    >
        Hello, World!
    </PluginDocumentSettingPanel>
);
registerPlugin( 'my-custom-panel', {render: MyCustomSideBarPanel } );

The above code will insert a new Panel in the Document Sidebar with the title of “My Custom Panel ” and will display “Hello, World!” as it’s content. If we want this panel to appear on every post type registered, then we’re done but what if we want to restrict this panel to just a single post type?