Routing is a way to serve web pages based upon the requested URL. In Angular which is used to build SPA, URLs are not served from the server and never reload the page. The URLs are strictly local in the browser and serve the page(components) from local. Every time you request an Url, the Angular router navigates to the new component and renders its template, and updates the history and URL.

Purpose of Routing

The angular router can interpret a browser URL as an instruction to navigate from/to the specific view. One can pass the optional parameters along with the supporting view component that help it decide what specific content to be present. We can bind the router to the links on a page, and it will navigate to the defined application view when the user clicks a link.

Steps to Configure Angular Routing

The Angular router has its library package which is @angular/router So we need to import what we need from it as we would from any other Angular package. It is an optional service that presents a particular component view.

There are following steps you have to follow to configure routing in Angular.

1. Step1: Define the routes

   Angular application routes are recommended to define within a separate module using an array as given below:

    
   import { NgModule } from '@angular/core';
   
   const routes: Routes = [
    { path: "", component: HomeComponent },
    { path: "about", component: AboutComponent }
   ];
   
   @NgModule({
    imports: [RouterModule.forRoot(routes)],
    exports: [RouterModule]
    })
    export class AppRoutingModule {}
   

2. Step2: Define the container

   RouterOutlet as the container where the router renders the component when the user requests a route.

    
    <div>
    <router-outlet></router-outlet>
    </div>
   

3. Step3: Define the links

   RouterLink directive is used to define links to a route name.

    
    <ul class="nav navbar-nav"> 
    <li>
    <a [routerLink]="['/']">Home</a>
    </li>
    <li>
    <a [routerLink]="['/about']">About</a>
    </li>
    </ul>
   

4. Step4: Define Route for 404

   In Angular, you can define a route that will be served, if the requested URL doesn't match any paths in the routes configuration. The ** characters are used to define the path for the route not found. You can define this path as given below:

    
    const routes: Routes = [
    { path: "", component: HomeComponent },
    { path: "about", component: AboutComponent },
    
    { path: "notfound", component: NotfoundComponent }, 
    { path: "**", redirectTo: "notfound" }
    ];
    

Note

1. In Angular routes configuration, the order of the routes matters. The angular router uses a first-match wins strategy when matching routes.

2. So more specific routes should be placed at the top level and less specific routes should be placed at the bottom in the routes configuration.

Location Strategies

Location Strategies in Angular defines how the URL/Request is being resolved and determines how your URL will look in the browser. Angular supports two types of Location Strategies

PathLocation Strategy

The PathLocation strategy is the default location strategy in Angular. In this strategy, the URL looks like the multi-page applications as http://localhost:4200/product. This strategy can be configured as given below:

 
 //step1: src/index.html
 <base href="/"> Use at main page i.e. index.html page

 //step2: src/app/app.routing.ts
 RouterModule.forRoot(appRoutes) in routing module
 

Advantages and Disadvantages of PathLocation Strategy

• Supports Server-Side Rendering
• SEO Friendly
• Older browsers don’t support

HashLocation Strategy

The hashLocation strategy you have to configure in Angular. In this strategy, the URL contains a hash character as http://localhost:4200/#/product. This strategy can be configured as given below:

 
 //step1: src/index.html
 <base href="/"> Use at main page i.e. index.html page

 //step2: src/app/app.routing.ts
 RouterModule.forRoot(appRoutes, {useHash: true}) in routing module
 

Advantages and Disadvantages of HashLocation Strategy

• Supported by all browsers
• Doesn't Support Server-Side Rendering
• Not SEO Friendly because of special character Hash

Child/Nested Routes

Sometimes you need to render one or more components on request on a component. In that case, child/nested routing helps us. This is a powerful feature in Angular router to render child/nested components using the route.

Configuring Child/Nested Routes

To define a child/nested route a Children option is used in the routes array as given below:

 
 const routes: Routes = [
 { path: "", component: HomeComponent },
 { path: "about", component: AboutComponent,
 children: [
 { path: "profile", component: ProfileComponent },
 { path: "changepassword", component: ChangepasswordComponent }
 ]
 }
 ];
 

 
 <h2>About Us</h2>
 <hr>
 <p>This is about us page for the company!</p>
 
 Activating the Child Routes 
 <a [routerLink]="['profile']">Profile</a>
 <a [routerLink]="['changepassword']">Change Password</a> 
 <router-outlet></router-outlet>

Summary

This article is meant to be a getting started to the concept of Routing in Angular. It's meant to show the most common uses, not all of them.

For any application, navigation is one of the important features that one can ask for. Even though a single-page application (SPA) does not have a multiple-page concept, it does moves from one view to another view. Providing clear and understandable navigation elements decides the success of an application pretty loudly.

Read More: Best Angular Interview Question and Answer