The difference between runtime-config and config is execution timing, runtime-config is evaluated while your app running in browser. Therefor, function, jsx, import and other browser-runnable snippets can be used.

node exclusive dependencies should not work.

As convention, src/app.tsx is the place you will put the runtime-config.

Modify the opts of clientRender function.

e.g. Modify the render root element in micro front-end solution.

let isSubApp = false;
export function modifyClientRenderOpts(memo) {
  return {
    ...memo,
    rootElement: isSubApp ? 'sub-root' : memo.rootElement,    
  };
}

Modify routing.

For example, prepend a new route /foo before all other routes.

export function patchRoutes({ routes }) {
  routes.unshift({
    path: '/foo',
    exact: true,
    component: require('@/extraRoutes/foo').default,
  });
}

For example, work with render, modify routes based on API response.

let extraRoutes;

export function patchRoutes({ routes }) {
  merge(routes, extraRoutes);
}

export function render() {
  fetch('/api/routes').then((res) => { extraRoutes = res.routes })
}

Notice：

• Modify routes instead of returning a new one

Overwrite render.

For example, check authority before rendering

import { history } from 'umi';

export function render(oldRender) {
  fetch('/api/auth').then(auth => {
    if (auth.isLogin) { oldRender() }
    else { history.push('/login'); }
  });
}

Change something at route initialization/changing phase.

For example, event tracking and analysis:

export function onRouteChange({ location, routes, action }) {
  bacon(location.pathname);
}

For example, setup title:

export function onRouteChange({ matchedRoutes }) {
  if (matchRoutes.length) {
    document.title = matchedRoutes[matchRoutes.length - 1].route.title || '';
  }
}

Modify root component being passed to react-dom.

For example, wrap a Provider:

export function rootContainer(container) {
  return React.createElement(ThemeProvider, null, container);
}

Since umi support modifing runtime-config via plugin, which means you may find more runtime-config options with plugins you involved.