Is it ok to use ReactDOMServer.renderToString in the browser in areas where React isn't directly managing the DOM?

I'm working on an app using Leaflet (via react-leaflet). Leaflet directly manipulates the DOM. The react-leaflet library doesn't change that, it just gives you React components that you can use to control your Leaflet map in a React-friendly way.

In this app, I want to use custom map markers that are divs containing a few simple elements. The way to do that in Leaflet is to set your marker's icon property to a DivIcon, in which you can set your custom HTML. You set that inner HTML by setting the DivIcon's html property to a string containing the HTML. In my case, I want that HTML to be rendered from a React component.

In order to do that, it seems like the correct approach is to use ReactDOMServer.renderToString() to render the Component that I want inside the map marker into a string, which I would then set as the html property of the DivIcon:

MyMarker.js:

import React, { Component } from 'react'
import { renderToString } from 'react-dom/server'
import { Marker } from 'react-leaflet'
import { divIcon } from 'leaflet'

import MarkerContents from './MarkerContents'

export class MyMarker extends Component {
  render() {
    const markerContents = renderToString(<MarkerContents data={this.props.data} />)
    const myDivIcon = divIcon({
      className: 'my-marker',
      html: markerContents
    })
    
    return (
      <Marker
        position={this.props.position}
        icon={myDivIcon} />
    )
  }
}

However, according to the React docs:

> This [renderToString] should only be used on the server.

Is this a strict rule, or is it only meant to dissuade people from circumventing ReactDOM's efficient management of the DOM?

I can't think of another (better) way to accomplish what I'm after. Any comments or ideas would be greatly appreciated.

According to the new documentation: https://reactjs.org/docs/react-dom-server.html

> The following methods can be used in both the server and browser > environments: > > - renderToString() > - renderToStaticMarkup()

I know it is too old question, but since it has not been answered I wanted to share my thoughts.

I was using the same thing, renderToString, but as the documentation recommends not to use it on client-side, I achieved it in another way, by using the react-dom's render method to render the custom component into div

var myDiv = document.createElement('div');

ReactDOM.render(
  <MarkerContents data={this.props.data} />,
  myDiv
);

var myIcon = L.divIcon({ 
    iconSize: new L.Point(50, 50), 
    html: myDiv.innerHTML
});

As Thomas already said, yes, you can use renderToString on the client. Just to be clear though, you will need to import ReactDOMServer on the client, which may seem counter-intuitive but appears to be correct. Example (on the client):

import React from 'react';
import ReactDOMServer from 'react-dom/server';

const MyComp = (props) => {
  const html = ReactDOMServer.renderToString(<div>{someFunc(props)}</div>);
  // do something with your html, then
  return <div dangerouslySetInnerHTML={{__html: html}}></div>;
};

I had the exact same problem with leaflet and ended up solving the problem by thinking with portals.

import React, { useEffect, useMemo,useState } from "react";
import ReactDOM from "react-dom";
import { useLeafletContext } from "@react-leaflet/core";
import * as L from "leaflet";

/**
 * @type { React.FC<{
 *    positionX?: number
 *    positionY?: number
 *    width?: number
 *    height?:number
 * }> }
 * */
const LeafletChild = ({ children, positionX=0, positionY=0, width, height }) => {
  const context = useLeafletContext();
  const [divElement] = useState(() => document.createElement("div"));
  const icon = useMemo(() => L.divIcon({ iconSize: new L.Point(height, width), html: divElement }), [height,width, divElement]);
  const marker = useMemo(() => L.marker([0,0], { icon }), [icon]);
  useEffect(()=>{
    marker.setLatLng([positionY, positionX])
  },[positionY,positionX, marker])

  useEffect(() => {
    const container = context.layerContainer || context.map;
    container.addLayer(marker);
    return () => container.removeLayer(marker);
  }, [context, marker]);
  return ReactDOM.createPortal(children, divElement);
};

Somwhere else...

<LeafletChild>
  <div onClick={()=>setSomeBool(!someBool)}>
    anything you want here like...{`${someBool}`}
  </div>
</LeafletChild>