gatsby-ssr.tsx

import { GatsbySSR, RenderBodyArgs, WrapRootElementNodeArgs } from 'gatsby';
import React from 'react';
import { HelmetProvider, HelmetServerState } from 'react-helmet-async';

const context: { helmet?: HelmetServerState } = {};

export const onRenderBody: GatsbySSR['onRenderBody'] = ({
    setHeadComponents,
    setHtmlAttributes,
    setBodyAttributes
}: RenderBodyArgs): void => {
    const { helmet } = context;

    if (helmet) {
        const baseComponent = helmet.base.toComponent();
        const titleComponent = helmet.title.toComponent() as unknown as any[];
        const components = [
            helmet.priority.toComponent(),
            helmet.meta.toComponent(),
            helmet.link.toComponent(),
            helmet.style.toComponent(),
            helmet.script.toComponent(),
            helmet.noscript.toComponent()
        ];

        setHeadComponents(
            titleComponent[0]?.props.children
                ? [baseComponent, titleComponent, ...components]
                : [baseComponent, ...components]
        );

        setHtmlAttributes(helmet.htmlAttributes.toComponent());
        setBodyAttributes(helmet.bodyAttributes.toComponent());
    }
};

export const wrapRootElement: GatsbySSR['wrapRootElement'] = ({
    element
}: WrapRootElementNodeArgs): React.ReactElement => (
    <HelmetProvider context={context}>{element}</HelmetProvider>
);