With the React-Helmet you can put your metadata in the render-function of your Component like this:

render(){ 

    return <div>

        <Helmet>

              <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">

        </Helmet>

        [...]

    </div>

}

Look at the Helmet documentation for further information.