Simple HOC for fetching data that is compatible with the SSR technique described by @BenLu here: https://medium.com/@benlu/ssr-with-create-react-app-v2-1-ee83fb767327

withInitialData.js

import React, { Component } from 'react';

const hasDataForThisKey = (staticContext) =>
  (key) => staticContext && Object.keys(staticContext.data).includes(key);

const windowHasDataForThisKey = (window) =>
  (key) => Object.keys(window.__DATA__).includes(key);

export default ({
  key,
  prop,
  getData,
}) => (WrappedComponent) => {
  class SSRCompatibleComponent extends Component {
    constructor(props) {
      super(props);

      this.state = {};
    }

    async componentWillMount() {
      this._handleData();
    }

    async _handleData() {
      const { staticContext } = this.props;

      if (hasDataForThisKey(staticContext)(key)) {
        const data = staticContext.data[key];
        this._setData(data);
      } else if (staticContext) {
        staticContext.data[key] = this._getData();
      } else if (!staticContext && windowHasDataForThisKey(window)(key)) {
        const data = window.__DATA__[key];
        window.__DATA__[key] = null;

        this._setData(data);
      } else if (!staticContext) {
        const data = await this._getData();
        this._setData(data);
      }
    }

    _setData(data) {
      this.setState({
        ...this.state,
        [prop]: data,
      })
    }

    async _getData() {
      const { props } = this;
      const data = await getData({ props });

      return data;
    }

    render() {
      return (
        <WrappedComponent
          {...this.props}
          {...this.state}
        />
      );
    }
  }

  return SSRCompatibleComponent;
}

For details of how to configure your express server to work with this, please see:

https://medium.com/@benlu/ssr-with-create-react-app-v2-1-ee83fb767327