Eine vollständige Anleitung für Anfänger zum Reagieren des Routers (einschließlich Router-Hooks)

Programmierung

React ist eine JavaScript-Bibliothek zum Erstellen von Benutzeroberflächen. Wir können es auch erweitern, um mithilfe von React Router mehrseitige Anwendungen zu erstellen. Dies ist eine Bibliothek von Drittanbietern, die das Routing in unseren React-Apps ermöglicht.

In diesem Tutorial werden wir alles behandeln, was Sie wissen müssen, um mit React Router zu beginnen.

  • Projekt einrichten
  • Was ist Routing?
  • Einrichten des Routers
  • Routen rendern
  • Verwenden von Links zum Wechseln von Seiten
  • Routenparameter übergeben
  • Programmgesteuert navigieren
  • Weiterleiten auf eine andere Seite
  • Weiterleiten auf eine 404-Seite
  • Routen bewachen
  • Router Hooks
  • useHistory
  • useParams
  • useLocation
  • Abschließende Gedanken
  • Nächste Schritte

Projekt einrichten

Um mitmachen zu können, müssen Sie eine neue React-App erstellen, indem Sie den folgenden Befehl in Ihrem Terminal ausführen:

npx create-react-app react-router-guide

Fügen Sie dann der App.jsDatei die folgenden Codezeilen hinzu :

import React from "react"; import "./index.css" export default function App() { return (   
  • Home
  • About
  • Contact
   ); } // Home Page const Home = () => (  
Home
   ); // About Page const About = () => (  
About
   ); // Contact Page const Contact = () => (  
Contact
   ); const FakeText = () => ( 
 Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. 
 )

Wenn Sie bereit sind, beantworten wir zunächst eine wichtige Frage: Was ist Routing?

Was ist Routing?

Routing ist die Fähigkeit, dem Benutzer verschiedene Seiten anzuzeigen. Das bedeutet, dass der Benutzer zwischen verschiedenen Teilen einer Anwendung wechseln kann, indem er eine URL eingibt oder auf ein Element klickt.

Wie Sie vielleicht bereits wissen, wird React standardmäßig ohne Routing geliefert. Und um es in unserem Projekt zu aktivieren, müssen wir eine Bibliothek namens React-Router hinzufügen.

Um es zu installieren, müssen Sie den folgenden Befehl in Ihrem Terminal ausführen:

yarn add react-router-dom

Oder

npm install react-router-dom

Nachdem wir unseren Router erfolgreich installiert haben, können Sie ihn im nächsten Abschnitt verwenden.

aufgeregt

Einrichten des Routers

Routing in unserem Reagieren App, wir müssen zuerst Import zu ermöglichen , BrowserRouteraus react-router-dom.

Geben Sie in die App.jsDatei Folgendes ein:

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router } from "react-router-dom"; export default function App() { return (    
  • Home
  • About
  • Contact
    ); }

Dies sollte alles in unserer App enthalten, wo Routing benötigt wird. Das heißt, wenn wir Routing in unserer gesamten App benötigen, müssen wir unsere höhere Komponente mit umschließen BrowserRouter.

Übrigens müssen Sie nicht BrowserRouter as Routerwie hier umbenennen , ich möchte nur die Dinge lesbar halten.

Ein Router allein macht nicht viel. Fügen wir also im nächsten Abschnitt eine Route hinzu.

Routen rendern

Um Routen zu rendern, müssen wir die RouteKomponente aus dem Router-Paket importieren .

Fügen Sie in Ihre App.jsDatei den folgenden Code ein:

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route } from "react-router-dom"; export default function App() { return (    
  • Home
  • About
  • Contact
Welcome!
} />   ); }

Fügen Sie es dann dort hinzu, wo wir den Inhalt rendern möchten. Die RouteKomponente hat mehrere Eigenschaften. Aber hier brauchen wir nur pathund render.

path: der Weg der Route. Hier /definieren wir den Pfad der Homepage.

render: will display the content whenever the route is reached. Here, we'll render a welcome message to the user.

In some cases serving routes like that is perfectly fine. But imagine a case when we have to deal with a real component – using render may not be the right solution.

So, how can we display a real component? Well, the Route component has another property named component.

Let's update our example a bit to see it in action.

In your App.js file, add the following code:

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route } from "react-router-dom"; export default function App() { return (    
  • Home
  • About
  • Contact
     ); } const Home = () => (  
Home
   );

Now, instead of rendering a message, our route will load the Home component.

To get the full power of React Router, we need to have multiple pages and links to play with. We already have pages (components if you want, too), so now let's add some links so we can switch between pages.

Using links to switch pages

To add links to our project, we will use the React Router again.

In your App.js file, add the following code:

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route, Link } from "react-router-dom"; export default function App() { return (    
  • Home
  • About
  • Contact
       ); } const Home = () => (  
Home
   ); const About = () => (  
About
   ); const Contact = () => (  
Contact
   );

After importing Link, we have to update our navigation bar a bit. Now, instead of using a tag and href, React Router uses Link and to to, well, be able to switch between pages without reloading it.

Then, we need to add two new routes, About and Contact, to be able to switch between pages or components.

Now, we can go to different parts of our app through links. But there is an issue with our router: the Home component is always displayed even if we switch to other pages.

This is because React Router will check if the path defined starts with /. If that's the case, it will render the component. And here, our first route starts with /, so the Home component will be rendered each time.

However, we can still change the default behavior by adding the exact property to Route.

In App.js, add:

By updating the Home route with exact, now it will be rendered only if it matches the full path.

We can still enhance it by wrapping our routes with Switch to tell to React Router to load only one route at a time.

In App.js, add:

import { BrowserRouter as Router, Route, Link, Switch } from "react-router-dom";

Now that we have new links, let's use them to pass parameters.

Passing route parameters

To pass data between pages, we have to update our example.

In your App.js file, add the following code:

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route, Link, Switch } from "react-router-dom"; export default function App() { const name = 'John Doe' return (    
  • Home
  • About
  • Contact
         ); } const Home = () => (  
Home
   ); const About = ({match:{params:{name}}}) => ( // props.match.params.name  
About {name}
   ); const Contact = () => (  
Contact
   );

As you can see here, we start by declaring a new constant name which will be passed as a parameter to the About page. And we append name to the corresponding link.

With that, we now have to update the About route by adjusting its path to receive name as a parameter path="/about/:name".

Now, the parameter will be received as props from the About component. The only thing we have to do now is destructure the props and get back the name property. By the way, {match:{params:{name}}} is the same as props.match.params.name.

We've done a lot up to this point. But in some cases we don't want to use links to navigate between pages.

Sometimes, we have to wait for an operation to finish before navigating to the next page.

zustimmen

So, let's handle that case in the next section.

Navigating programmatically

The props we receive have some convenient methods we can use to navigate between pages.

In App.js, add:

const Contact = ({history}) => (  
Contact
  history.push('/') } >Go to home   );

Here, we pull the history object from the props we receive. It has some handy methods like goBack, goForward, and so on. But here, we will use the push method to be able to go to the Home page.

Now, let's handle the case when we want to redirect our user after an action.

Redirecting to another page

The React Router has another component named Redirect. As you guessed, it helps us redirect the user to another page

In App.js, add:

import { BrowserRouter as Router, Route, Link, Switch, Redirect } from "react-router-dom"; const About = ({match:{params:{name}}}) => ( // props.match.params.name  { name !== 'John Doe' ?  : null } 
About {name}
   );

Now, if the name passed as a parameter is not equal to John Doe, the user will be redirected to the home page.

You could argue that you should redirect the user with props.history.push('/). Well, the Redirect component replaces the page and therefore the user can't go back to the previous page. But, with the push method they can. However, you can use props.history.replace('/) to mimic the Redirect behavior.

Now let's move on and handle the case when the user hits a route that doesn't exist.

Redirecting to a 404 page

To redirect the user to a 404 page, you can create a component to show it. But here, to keep things simple, I will just display a message with render.

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route, Link, Switch } from "react-router-dom"; export default function App() { const name = 'John Doe' return (    
  • Home
  • About
  • Contact
404: page not found
} />    ); }

The new route we've added will catch every path that doesn't exist and redirect the user to the 404 page.

Now, let's move on and learn how to protect our routes in the next section.

Guarding routes

There are many ways to protect routes to React. But here I will just check if the user is authenticated and redirect them to the appropriate page.

import React, { Fragment } from "react"; import "./index.css" import { BrowserRouter as Router, Route, Link, Switch } from "react-router-dom"; export default function App() { const name = 'John Doe' const isAuthenticated = false return (    
  • Home
  • About
  • Contact
    { isAuthenticated ?     :  }    ); }

As you can see here, I declared a variable to mimic authentication. Then, check if the user is authenticated or not. If they are, render protected pages. Otherwise redirect them to the home page.

We've covered a lot up to this point, but an interesting part remains: router hooks.

Let's move to the final section and introduce Hooks.

Ja

Router Hooks

Router hooks make things much easier. Now you can access the history, location, or parameters in an easy and elegant way.

useHistory

The useHistory hook gives us access to the history instance without pulling it from props.

import { useHistory } from "react-router-dom"; const Contact = () => { const history = useHistory(); return (  
Contact
  history.push('/') } >Go to home  ) };

useParams

This hook helps us get the parameter passed on the URL without using the props object.

import { BrowserRouter as Router, Route, Link, Switch, useParams } from "react-router-dom"; export default function App() { const name = 'John Doe' return (    
  • Home
  • About
        ); } const About = () => { const { name } = useParams() return ( // props.match.params.name  { name !== 'John Doe' ?  : null } 
About {name}
   ) };

useLocation

Dieser Hook gibt das Standortobjekt zurück, das die aktuelle URL darstellt.

import { useLocation } from "react-router-dom"; const Contact = () => { const { pathname } = useLocation(); return (  
Contact
Current URL: {pathname}
  ) };

Abschließende Gedanken

React Router ist eine erstaunliche Bibliothek, mit der wir von einer einzelnen Seite zu einem mehrseitigen Anwendungsgefühl mit hervorragender Benutzerfreundlichkeit wechseln können. (Denken Sie daran - am Ende des Tages ist es immer noch eine App mit nur einer Seite).

Und jetzt können Sie mit Router-Hooks sehen, wie einfach und elegant sie sind. Sie sind definitiv etwas, das Sie in Ihrem nächsten Projekt berücksichtigen sollten.

Sie können mehr meiner Artikel in meinem Blog lesen.

Nächste Schritte

Reagieren Sie auf die Router-Dokumentation

Foto von Joshua Sortino auf Unsplash