In React, OK to always call ReactDOM.hydrate instead of ReactDOM.render?

Question

I've got code like the following where I'm calling ReactDOM.hydrate. This is shared code that sometimes gets called from the node server and sometimes in the client browser. Do I need to do anything different (then calling hydrate) when calling it on the client only. Normally, I'd call render.

const render = Component => {
 ReactDOM.hydrate(
    <Router history={browserHistory}>
        <FullPage />
    </Router>,
    document.getElementById('root')
 )
}

render(App);

Answer 1

hydrate do works similar to render on client side whether the HTML has server rendered markup or not, but when there is no markup previously like not SSR then hydrate produces some warnings but, it will render your markup as expected. A better way to solve this would be to check if its SSR (assuming root as your parent div id) :

var isMarkupPresent = document.getElementById('root').hasChildNodes();

and then you can either render or hydrate:

isMarkupPresent ? hydrate(...) ? render(...)