React Router Introduction

By: Ryan Florence

256   12   91207

Uploaded on 02/01/2017

An quick introduction to the React Router v4 API.

Comments (2):

By anonymous    2017-09-20

If you are targeting browser environments, you need to use react-router-dom package, instead of react-router. They are following the same approach as React did, in order to separate the core, (react) and the platform specific code, (react-dom, react-native ) with the subtle difference that you don't need to install two separate packages, so the environment packages contain everything you need. You can add it to your project as:

yarn add react-router-dom

or

npm i -S react-router-dom

The first thing you need to do is to provide a <BrowserRouter> as the top most parent component in your application. <BrowserRouter> uses the HTML5 history API and manages it for you, so you don't have to worry about instantiating it yourself and passing it down to the <BrowserRouter> component as a prop (as you needed to do in previous versions).

In V4, for navigating programatically you need to access the history object, which is available through React context, as long as you have a <BrowserRouter> provider component as the top most parent in your application. The library exposes through context the router object, that itself contains history as a property. The history interface offers several navigation methods, such as push, replace and goBack, among others. You can check the whole list of properties and methods here.

Important Note to Redux/Mobx users

If you are using redux or mobx as your state management library in your application, you may have come across issues with components location-aware that are not re-rendered after triggering an URL update

That's happening because react-router passes location to components using the context model.

Both connect and observer create components whose shouldComponentUpdate methods do a shallow comparison of their current props and their next props. Those components will only re-render when at least one prop has changed. This means that in order to ensure they update when the location changes, they will need to be given a prop that changes when the location changes.

The 2 approaches for solving this are:

  • Wrap your connected component in a pathless <Route />. The current location object is one of the props that a <Route> passes to the component it renders
  • Wrap your connected component with the withRouter higher-order component, that in fact has the same effect and injects location as a prop

Setting that aside, there are four ways to navigate programatically, ordered by recommendation:

1.- Using a <Route> Component

It promotes a declarative style. Prior to v4, <Route /> components were placed at the top of your component hierarchy, having to think of your routes structure beforehand. However, now you can have <Route> components anywhere in your tree, allowing you to have a finer control for conditionally rendering depending on the URL. Route injects match, location and history as props into your component. The navigation methods (such as push, replace, goBack...) are available as properties of the history object.

There are 3 ways to render something with a Route, by using either component, render or children props, but don't use more than one in the same Route. The choice depends on the use case, but basically the first two options will only render your component if the path matches the url location, whereas with children the component will be rendered whether the path matches the location or not (useful for adjusting the UI based on URL matching).

If you want to customise your component rendering output, you need to wrap your component in a function and use the render option, in order to pass to your component any other props you desire, apart from match, location and history. An example to illustrate:

import { BrowserRouter as Router } from 'react-router-dom'

const ButtonToNavigate = ({ title, history }) => (
  <button
    type="button"
    onClick={() => history.push('/my-new-location')}
  >
    {title}
  </button>
);

const SomeComponent = () => (
  <Route path="/" render={(props) => <ButtonToNavigate {...props} title="Navigate elsewhere" />} />
)    

const App = () => (
  <Router>
    <SomeComponent /> // Notice how in v4 we can have any other component interleaved
    <AnotherComponent />
  </Router>
);

2.- Using withRouter HoC

This higher order component will inject the same props as Route. However, it carries along the limitation that you can have only 1 HoC per file.

import { withRouter } from 'react-router-dom'

const ButtonToNavigate = ({ history }) => (
  <button
    type="button"
    onClick={() => history.push('/my-new-location')}
  >
    Navigate
  </button>
);


ButtonToNavigate.propTypes = {
  history: React.PropTypes.shape({
    push: React.PropTypes.func.isRequired,
  }).isRequired,
};

export default withRouter(ButtonToNavigate);

3.- Using a Redirect component

Rendering a <Redirect> will navigate to a new location. But keep in mind that, by default, the current location is replaced by the new one, like server-side redirects (HTTP 3xx). The new location is provided by to prop, that can be a string (URL to redirect to) or a location object. If you want to push a new entry onto the history instead, pass a push prop as well and set it to true

<Redirect to="/your-new-location" push />

4.- Accessing router manually through context

A bit discouraged because context is still an experimental API and it is likely to break/change in future releases of React

const ButtonToNavigate = (props, context) => (
  <button
    type="button"
    onClick={() => context.router.history.push('/my-new-location')}
  >
    Navigate to a new location
  </button>
);

ButtonToNavigate.contextTypes = {
  router: React.PropTypes.shape({
    history: React.PropTypes.object.isRequired,
  }),
};

Needless to say there are also other Router components that are meant to be for non browser ecosystems, such as <NativeRouter> that replicates a navigation stack in memory and targets React Native platform, available through react-router-native package.

For any further reference, don't hesitate to take a look at the official docs. There is also a video made by one of the co-authors of the library that provides a pretty cool introduction to react-router v4, highlighting some of the major changes.

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