React Starter Kit Hot Router

client.js

/**
 * React Starter Kit (https://www.reactstarterkit.com/)
 *
 * Copyright © 2014-2016 Kriasoft, LLC. All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE.txt file in the root directory of this source tree.
 */

import 'babel-polyfill';
import ReactDOM from 'react-dom';
import FastClick from 'fastclick';
import Router from './routes';
import Location from './core/Location';
import { addEventListener, removeEventListener } from './core/DOMUtils';

let cssContainer = document.getElementById('css');
const appContainer = document.getElementById('app');
const context = {
  insertCss: styles => styles._insertCss(),
  onSetTitle: value => (document.title = value),
  onSetMeta: (name, content) => {
    // Remove and create a new <meta /> tag in order to make it work
    // with bookmarks in Safari
    const elements = document.getElementsByTagName('meta');
    Array.from(elements).forEach((element) => {
      if (element.getAttribute('name') === name) {
        element.parentNode.removeChild(element);
      }
    });
    const meta = document.createElement('meta');
    meta.setAttribute('name', name);
    meta.setAttribute('content', content);
    document
      .getElementsByTagName('head')[0]
      .appendChild(meta);
  },
};

// Google Analytics tracking. Don't send 'pageview' event after the first
// rendering, as it was already sent by the Html component.
let trackPageview = () => (trackPageview = () => window.ga('send', 'pageview'));

let HotRouter = Router;
function render(state) {
  HotRouter.dispatch(state, (newState, component) => {
    ReactDOM.render(component, appContainer, () => {
      // Restore the scroll position if it was saved into the state
      if (state.scrollY !== undefined) {
        window.scrollTo(state.scrollX, state.scrollY);
      } else {
        window.scrollTo(0, 0);
      }

      trackPageview();

      // Remove the pre-rendered CSS because it's no longer used
      // after the React app is launched
      if (cssContainer) {
        cssContainer.parentNode.removeChild(cssContainer);
        cssContainer = null;
      }
    });
  });
}

function run() {
  let currentLocation = null;
  let currentState = null;

  // Make taps on links and buttons work fast on mobiles
  FastClick.attach(document.body);

  // Re-render the app when window.location changes
  const unlisten = Location.listen(location => {
    currentLocation = location;
    currentState = Object.assign({}, location.state, {
      path: location.pathname,
      query: location.query,
      state: location.state,
      context,
    });
    render(currentState);
  });

  // Save the page scroll position into the current location's state
  const supportPageOffset = window.pageXOffset !== undefined;
  const isCSS1Compat = ((document.compatMode || '') === 'CSS1Compat');
  const setPageOffset = () => {
    currentLocation.state = currentLocation.state || Object.create(null);
    if (supportPageOffset) {
      currentLocation.state.scrollX = window.pageXOffset;
      currentLocation.state.scrollY = window.pageYOffset;
    } else {
      currentLocation.state.scrollX = isCSS1Compat ?
        document.documentElement.scrollLeft : document.body.scrollLeft;
      currentLocation.state.scrollY = isCSS1Compat ?
        document.documentElement.scrollTop : document.body.scrollTop;
    }
  };

  addEventListener(window, 'scroll', setPageOffset);
  addEventListener(window, 'pagehide', () => {
    removeEventListener(window, 'scroll', setPageOffset);
    unlisten();
  });

  if (module.hot) {
    module.hot.accept('./routes', () => {
      HotRouter = require('./routes').default;
      render(currentState);
    });
  }
}

// Run the application when both DOM is ready and page content is loaded
if (['complete', 'loaded', 'interactive'].includes(document.readyState) && document.body) {
  run();
} else {
  document.addEventListener('DOMContentLoaded', run, false);
}