Upgrading from 1.x

Having an existing Angular 1 application doesn't mean that we can't begin enjoying everything Angular 2 has to offer. That's beause Angular 2 comes with built-in tools for migrating Angular 1 projects over to the Angular 2 platform.

One of the keys to a successful upgrade is to do it incrementally, by running the two frameworks side by side in the same application, and porting Angular 1 components to Angular 2 one by one. This makes it possible to upgrade even large and complex applications without disrupting other work. The upgrade module in Angular 2 has been designed to make incremental upgrading seamless.

In this chapter we will look at a complete example of preparing and upgrading an application using the upgrade module. The app we're going to work on is Angular PhoneCat from the original Angular 1 tutorial, which is where many of us began our Angular adventures. Now we'll see how to bring that application to the brave new world of Angular 2.

During the process we'll learn

• How to prepare and align an Angular 1 application with Angular 2

• How to use the SystemJS module loader and TypeScript with Angular 1

• How to develop and test a hybrid Angular 1+2 application

• How to migrate an application to Angular 2 one component at a time

To follow along with the tutorial, clone the angular-phonecat repository and apply the steps as we go

Preparing for the Upgrade

In terms of project structure, this is where our work begins

This is actually a pretty good starting point. In particular, this organization follows the Angular Style Guide, which is an important preparation step before a successful upgrade.

• Each controller, factory, and filter is in its own source file, as per the Rule of 1.
• The core, phoneDetail, and phoneList modules are each in their own subdirectory. Those subdirectories contain the JavaScript code as well as the HTML templates that go with each particular feature. This is in line with the Folders-by-Feature Structure and Modularity rules.

TypeScript And Module Loading

Since we're going to be writing our Angular 2 code in TypeScript, it makes sense to bring in the TypeScript compiler even before we begin upgrading.

In order to use TypeScript's ES2015 module system to import and export code, we're going to need a JavaScript module loader. Our application doesn't currently use one, and is just using plain old <script> tags and the global window scope instead. We'll replace this approach with the SystemJS loader.

We will also start to gradually phase out the Bower package manager in favor of NPM. We'll install all new dependencies using NPM, and will eventually be able to remove Bower from the project.

Let's begin by installing the SystemJS and TypeScript packages to the project:

npm i systemjs --save
npm i typescript --save-dev

The Angular 1 framework doesn't come with built-in TypeScript type definitions. This means that if we want to have type checks for the calls we make to Angular 1 APIs, we should install its type definitions separately. For that we'll use the tsd TypeScript definition manager. Let's make sure we have it globally installed:

npm i -g tsd

We can then use tsd to install the type definitions for Angular 1 and the Jasmine unit test framework. This will add a typings directory to the project and install a number of .d.ts files under it:

tsd install angular angular-route angular-resource angular-mocks jasmine

In index.html, let's now enable SystemJS. Add a <script> tag that loads the SystemJS library and a second <script> tag that initializes it. These will replace the various <script> tags we had earlier for loading the application components:

This configuration tells SystemJS that we have a module called app.module that resides in the js subdirectory (relative to the index.html page). We then load that module using System.import. This will load and execute the app/app.module.js file.

We should also configure the TypeScript compiler so that it can understand our project. We'll add a tsconfig.json file to the project directory, just like we did in the Quickstart. It instructs the TypeScript compiler how to interpret our source files.

We are telling the TypeScript compiler to turn our TypeScript files to ES5 code bundled into SystemJS modules. In other words, our compiler target is something SystemJS can load and all major browsers are able to run.

Also add a tsc run script to package.json. We'll use it to start the TypeScript compiler:

We can now launch the TypeScript compiler from the command line. It will watch our .ts source files and compile them to JavaScript on the fly. Those compiled .js files are then loaded into the browser by SystemJS. This is a process we'll want to have continuously running in the background as we go along.

npm run tsc

The next thing we'll do is convert our JavaScript files to TypeScript and define their imports and exports. Each file should now explicitly export the things it wants to expose, and import the things it needs from other files. This is a departure from the previous approach which just relied on things being available on the global window scope.

Since TypeScript is a superset of ECMAScript 2015, which in turn is a superset of ECMAScript 5, we can simply switch the file extensions from .js to .ts and define the imports and exports. We don't need to make other changes to our existing code. Instead we'll introduce type annotations and other new features gradually over time.

Let's begin by adding references to the Angular 1.x .d.ts typing files to the main application file. Rename app.module.js to app.module.ts and add the following on top of the file:

The TypeScript compiler will now know what we mean when we reference Angular 1 APIs. It should already at this point be able to compile the app.module.ts file successfully.

Let's then go through the rest of our source files and convert them. We'll rename each one to a .ts file, and add the imports and exports it needs.

Beginning from the checkmark filter, here are the converted contents:

This file now has the filter factory function as the default export. Apart from the export, there's one other major change we've applied to the file, which is that it does not contain the registration of the filter into an Angular module. We will do that later in the core module's main file.

Moving to the Phone factory file, it now has the factory function as the default export:

The core module's main module file will now import both the checkmark filter and the Phone factory. This is where we actually register them into the Angular module. We then export the module itself as this file's default export:

Notice that with this organization pattern, the files that hold the application components themselves - filters and factories - aren't concerned with the makeup of Angular modules. That's just something we previously had to do because there were no other good solutions. Now we use a separate file just for the purpose of forming the Angular module.

Now switching to the phone detail module, we'll make similar changes here. In the controller file we export the controller function as the default export:

In the main module file we import the controller and register it into the Angular module, which itself is then exported:

Then we'll repeat the same steps once more for the phone list module. The controller file exports the controller function:

And the main module file imports the controller and registers it:

Finally, we can now pull everything together in app.module.ts. It here we'll import each of the three submodule files and register them as dependencies of the main application module:

Note that we don't have to repeat the submodule name strings here. Since the modules export themselves, we can just refer to the name attribute of each of them.

Before this converted version of the application will run, we need to change the way we're bootstrapping it. It is currently bootstrapped using the ng-app directive attached to the <html> element of the host page. This will no longer work because ng-app is processed when the page loads, and our application code will not be available at that point yet. It is loaded asynchronously by SystemJS instead.

We should switch to a JavaScript-driven bootstrap instead. As it happens, this is also how Angular 2 apps are bootstrapped, so the switch brings us one step closer to Angular as well. So, remove the ng-app attribute from index.html, and add this at the end of app.module.ts:

We now have a fully functional version of the application, all converted into TypeScript code and a modern module system! If you start the project HTTP server with npm start, you should see the fully functional application in your browser. On the other hand, if you were to try running the test suite, things wouldn't look quite that good yet. We also have to make our tests support our new module organization.

Preparing Tests

Our project has both E2E Protractor tests and some Karma unit tests in it. Both of those are going to need a bit of work.

Of these two, E2E tests are a lot easier to convert. By definition, E2E tests access our application from the outside by interacting with the various UI elements the app puts on the screen. E2E tests aren't really that concerned with the internal structure of the application components. That also means that although we've modified our project quite a bit, the E2E test suite should keep passing just as it was before. We haven't changed how the app behaves from the user's point of view.

What we can do is convert our E2E test code to TypeScript, like we've done with the production code. To do this, you can just rename the scenarios.js file to scenarios.ts. After that, you'll want to declare the global Protractor variables used in the file, so that the TypeScript compiler knows we're accessing them on purpose:

Once we add Angular 2 to the project, we'll be able to add more type safety to this file, because Angular 2 ships with the type definitions of the Protractor framework as well.

That pretty much takes care of E2E tests for now. For unit tests we're going to do a bit more. What we'll do is convert our existing unit tests to TypeScript as well as have them use imports to load in the code they need. We'll also need to tweak our Karma configuration so that it'll let SystemJS load the application files.

But first we should have some additional type definitions loaded, so that the TypeScript compiler can understand the Jasmine and ngMock APIs we're using in unit tests. Add a file called test_helper.ts to the test directory and add a reference to the Jasmine and mock type definitions we already installed earlier:

For Karma's SystemJS support we'll use a shim file that will tweak the way files get loaded, so that it happens through SystemJS:

We'll then update the Karma configuration file, so that it loads SystemJS and the shim file. We'll also change how the app and unit tests files themselves are loaded. We will watch them so that the test suite is triggered when changes occur, but we won't have Karma include them because that is now done by SystemJS and the shim.

Now we have the infrastructure in place and can convert the test files themselves. This mainly just consists for changing the file extensions of those files, and adding the necessary imports to them.

In the checkmark filter spec, we'll import the core module file, so that it is available when we load the corresponding Angular module:

We'll do the exact same thing for the phone factory spec:

In the phone detail controller spec, on the other hand, we should import the phone detail module:

Finally, the phone list controller spec should import the phone list module:

There's one more issue we have in our controller tests, which is that TypeScript isn't happy about compiling them at the moment. This is because we're using the custom Jasmine matcher toEqualData in both of them. Because this is something we define ourselves, it isn't included in the Jasmine type definitions that we installed using tsd.

We can add our own little type definition file for that extension, which extends the jasmine.Matchers interface and adds our custom matcher to it. This will satisfy the compiler and let us use our custom matcher while retaining the nice type safety features of TypeScript:

And now we have a fully functional test suite for our TypeScript-enabled application as well.

Enjoying The Benefits of TypeScript

Now that we have TypeScript, we can start benefiting from some of its other features in addition to the imports and exports that we're already using. There's a lot of value the language can provide in Angular 1 applications.

For one thing, TypeScript is a superset of ES2015. Any app that has previously been written in ES5 - like the PhoneCat example has - can with TypeScript start incorporating all of the JavaScript features that are new to ES2015. These include things like lets and consts, default function parameters, and destructuring assignments.

Another thing we can do is start adding type safety to our code, by adding type annotations. For instance, we can annotate the checkmark filter so that it expects booleans as arguments and returns strings. This makes it clearer what the filter is supposed to do, and makes it possible for the TypeScript compiler to notify us when we're trying to use it with incompatible types.

Another TypeScript feature we can make use of is classes. In particular, we can turn our controllers into classes. That way they'll be a step closer to becoming Angular 2 component classes, which will make our life easier once we do the upgrade.

Angular 1 expects controllers to be constructor functions, and that's what ES2015/TypeScript classes really are, and that means we can just register a class as a controller and Angular 1 will happily use it. We also won't need to make any changes to our test suite as the external behavior of the controllers will not change.

Here's what our new class for the phone list controller looks like.

What was previously done in the controller function is now done in the class constructor function. The class additionally declares three members: The array of phones, the name of the current sort key, and the search query. These are all things we have already been attaching to the controller, but that weren't explicitly declared anywhere. The last one of these isn't actually used in the TypeScript code since it's only referred to in the template, but for the sake of clarity we want to define all the members our controller will have.

In the Phone detail controller we'll have two members: One for the phone that the user is looking at and another for the URL of the currently displayed image. We can additionally introduce a TypeScript interface that explicitly defines what we expect the $routeParams object to contain when it is passed to the controller. This interface is not exported and is just used internally inside this module:

This makes our controller code look a lot more like Angular 2 already. We're all set to actually introduce Angular 2 into the project.

If we had any Angular 1 services in the project, those would also be a good candidate for converting to classes, since like controllers, they're also constructor functions. But we only have the Phone factory in this project, and that's a bit special since it's an ngResource factory. So we won't be doing anything to it in the preparation stage, but will instead turn it directly into an Angular 2 service in the next section.

Gradually Upgrading to Angular 2

Having completed our preparation work, let's get going with the Angular 2 upgrade itself. We'll do this incrementally with the help of the upgrade module that comes with Angular 2. By the time we're done, we can remove Angular 1 from the project completely, but the key is to do it piece by piece without breaking the application.

Let's install Angular 2 into the project. Add the Angular 2 dependencies to package.json as described in the package.json appendix of the Quickstart. Then run:

npm i

We can then load Angular 2 into the application by adding some <script> tags to index.html. They should go before the <script> tag with the System.config() invocation:

The first two scripts are for adding some ES6 features to older browsers that don't natively support them. The last three bring in Angular 2 itself.

While we're at it, let's also load the same files into unit tests by updating the Karma config:

Bootstrapping Hybrid 1+2 Applications

What we'll do next is bootstrap the application as a hybrid application that supports both Angular 1 and Angular 2 components. Once we've done that we can start converting the individual pieces to Angular 2.

At this point we need to do add the Angular 2 type definitions into app.ts, so that the TypeScript compiler knows what we're talking about when we use Angular 2 APIs. Unlike with Angular 1, we don't need to install or refer to these type definitions in our source code, because Angular 2 comes with them included. What we do need to do is set the TypeScript compiler's moduleResolution option to node, so that it knows to look for these definitions from the angular2 NPM package.

Angular 2 bundles the Jasmine type definitions we need in tests, which means that the Jasmine type definitions we installed with tsd are now redundant. We might as well remove them so that there's no confusion about which ones we're using.

rm -r typings/jasmine

Also remove the reference to those type definitions from test/test_helper.ts.

The same also goes for Protractor: Angular 2 comes with the types of the Protractor APIs, so it's safe to remove the declare var line from scenarios.ts.

To boostrap a hybrid application, we first need to initialize an UpgradeAdapter. This is an object that comes with the angular2/upgrade module. It provides the glue that joins the two versions of the framework together. It can be used to

• Upgrade Angular 1 directives to Angular 2 components
• Downgrade Angular 2 components to Angular 1 directives
• Upgrade Angular 1 factories, services, and providers to Angular 2 services
• Downgrade Angular 2 services to Angular 1 factories
• Bootstrap and manage hybrid Angular 1+2 applications

Together these features allow us to very flexibly mix and match the two frameworks in our apps. This flexibility is great because there are many different kinds of Angular code out there. Even within a single app, we may need different strategies to deal with different kinds of components.

Let's import the UpgradeAdapter class into app.module.ts:

We can then make an adapter by instantiating the class:

Now we can use that adapter to bootstrap our application as a hybrid. Instead of calling angular.bootstrap, we must call upgradeAdapter.bootstrap, but the function arguments remain the same: They are still the element that will become the root of the application, and the names of the root Angular 1.x modules that we want to include:

We are now running both Angular 1 and 2 at the same time. That's pretty exciting! We're not running any actual Angular 2 components yet though, so let's do that next.

Upgrading Services

The first piece we'll port over to Angular 2 is the Phone factory, which resides in app/js/core/phones.factory.ts and makes it possible for controllers to load phone information from the server. Right now it's implemented with ngResource and we're using it for two things:

• For loading the list of all phones into the phone list controller
• For loading the details of a single phone into the phone detail controller.

We can replace this implementation with an Angular 2 service class, while keeping our controllers in Angular 1 land. In the new version we'll just use the the Http service from Angular 2 instead of ngResource.

The Http service isn't included in the main Angular 2 bundle, so we need to include it in index.html separately. As the service uses RxJS Observables, we also need to bring in the RxJS bundle:

We'll also do the same in karma.conf.js so that Http will be available in unit tests:

Before the Http service is available for injection, we still need to register it into our application's dependency injector. We should import the HTTP_PROVIDERS constant in app.module.ts:

In a regular Angular 2 application we would now pass HTTP_PROVIDERS into the application bootstrap function. But we can't do that in a hybrid application such as the one we're working on. That's because the bootstrap method of UpgradeAdapter expects Angular 1 modules as dependencies, not Angular 2 providers.

What we must do instead is register HTTP_PROVIDERS into the UpgradeAdapter separately. It has a method called addProvider for that purpose:

Now we're ready to upgrade the Phones factory itself. We'll put the Angular 2 implementation in a new file called Phones.ts in the core module. It will be a TypeScript class decorated as @Injectable:

Note that with Angular 2 we're switching to a new file naming scheme, and won't be using the feature.type.ts naming convention anymore.

The @Injectable decorator will attach some dependency injection metadata to the class, letting Angular 2 know about its dependencies. As described by our Dependency Injection Guide, this is a marker decorator we need to use for classes that have no other Angular 2 decorators but still need to have their dependencies injected.

In its constructor the class expects to get the Http service. It will be injected to it and it is stored as a private field. The service is then used in the two instance methods, one of which loads the list of all phones, and the other the details of a particular phone:

The methods now return Observables of type Phone and Phone[]. This is a type we don't have yet, so let's add a simple interface for it:

Here's the full, final code for the service:

Notice that we're importing the map operator of the RxJS Observable separately. We need to do this for all RxJS operators that we want to use, since Angular 2 does not load all of them by default.

The new Phones service now has the same features that the original, ngResource based service did. You can remove the old phones.factory.ts file. Now we just need to register the new service into the application, so that our Angular 1 controllers will be able to use it.

UpgradeAdapter has a downgradeNg2Provider method for the purpose of making Angular 2 services available to Angular 1 code. The problem is that we don't have our UpgradeAdapter available in core.module.ts where the Phones service should be registered. We only have it in app.module.ts. There should only be one UpgradeAdapter in an application, so we need to find a way to share our instance between the two code modules.

What we'll do is create a new module that instantiates UpgradeAdapter and exports the instance. We can then just pull it in wherever we need it, so that we're using the same object everywhere. Let's put this new file under core:

In app.module.ts we should now just import this adapter instead of making a separate one:

Also remove the line from app.module.ts that is instantiating UpgradeAdapter. It's no longer needed since we import the instance from elsewhere.

We'll then do the same in core.module.ts as well. Then we can register the Phones service into it. While doing that, we can remove the module's dependency to ngResource, which we're no longer using.

Note that we actually needed to do two registrations here:

1. Register Phones as an Angular 2 provider with the addProvider method. That's the same method that we used earlier for HTTP_PROVIDERS.
2. Register an Angular 1 factory called phones, which will be a downgraded version of the Phones service.

At this point we can switch our two controllers to use the new service instead of the old one. We $inject it as the downgraded phones factory, but it's really an instance of the Phones class and we can annotate its type accordingly:

What we have here are two Angular 1 controllers using an Angular 2 service! The controllers don't need to be aware of this, though the fact that the service returns Observables and not Promises is a bit of a giveaway. In any case, what we've achieved is a migration of a service to Angular 2 without having to yet migrate the controllers that use it.

To bring our test suite up to speed with the changes, we should first enable the Angular 2 test support library in our unit test suite. We first need to add the angular testing bundle to list of files that Karma is loading:

Then we'll update the Karma test shim. It should load the Angular 2 browser adapter before getting to the spec files:

Now, let's look at the tests for the service itself. What we used to have in phones_factory_spec.js was a fairly simple test that simply checks if the factory exists and is available for injection. We can now do that same test in Angular 2. Rename phones.factory.spec.ts to Phones.spec.ts and set the contents as follows:

Here we first load the Phones provider and then test that an instance of Phones can in fact be injected. We also need to load HTTP_PROVIDERS since it is a dependency of Phones.

For the controller tests, we can first of all at this point get rid of the custom toEqualData custom matcher. It was added because ngResource attaches attributes to the data that we don't want to compare in tests. We're no longer using ngResource, so we can simply use the built-in toEqual for comparisons. This means we can remove the test/jasmine_matchers.d.ts file at this point.

Now, in the phone detail controller we have been testing that the phone details with the id given in the route params are fetched over HTTP and put on the scope. We can continue doing that, but we'll need to change the structure of the test a bit. Instead of using the Angular 1 mock HTTP backend, we'll just mock out the get method of the Phones service, which is what the controller is now using to load what it needs. As the mocked value, we're returning an Observable that will emit a single value - the mock phone data:

In the phone list controller we'll do something very similar: We mock out the query method of the Phones service, and check that the controller makes the resulting value available:

Upgrading Controllers to Components

Next, let's upgrade our Angular 1 controllers to Angular 2 components. We'll do it one at a time, while still keeping the application in hybrid mode. As we make these conversions, we'll also be defining our first Angular 2 pipes.

Let's look at the phone list controller first. Right now it is a TypeScript class, which is paired with an HTML template by the route configuration in app.ts. We'll be turning it into an Angular 2 component.

Rename phone_list.controller.ts to PhoneList.ts. Then rename the controller class inside to just PhoneList and decorate it as a @Component:

The selector attribute is a CSS selector that defines where on the page the component should go. It will match elements by the name of pc-phone-list. It is a good idea to always use application-specific prefixes in selectors so that they never clash with built-in ones, and here we're using pc-, which is short for "PhoneCat".

The templateUrl defines the location of the component template. It points to our existing template file

Both of these attributes are things that were defined externally for the controller, but for the component are things that it defines itself. This will affect how we use the component in the router.

We now also need to convert the template of this component into Angular 2 syntax. In the search controls we need to use Angular 2 syntax for the two ngModels

In the list we need to replace the ng-repeat with an *ngFor and its #var of iterable syntax, as described in our Template Syntax guide.

For the images, we can replace ng-src with the standard src, but will use a property binding. Note that we're also adding a name CSS class for the phone name. This is something we'll need for our Protractor tests:

In the module file we're going to plug this component into our application. Instead of registering a controller, we register a pcPhoneList directive. The directive is a downgraded version of our component, and the UpgradeAdapter handles the bridging between the two:

The <angular.IDirectiveFactory> type annotation here is to let the TypeScript compiler know that the return value of the downgrade method call will be something that can be used as a directive factory.

To complete the switch, we should change our route configuration in app.module.ts. Instead of using the controller and template, it can just instantiate our component. We can do that by using a simple template that uses the directive we just registered:

When the application runs, the Angular 1.x directive compiler will match the element in the template to the pcPhoneList directive, which is actually an Angular 2 component!

The remaining issue with the phone list is the use of filters in its template: It is referring to the filter filter and the orderBy filter, and relying on them to filter and sort the phone list, respectively. These pipes do not exist in Angular 2, so we're going to need to do the filtering and sorting ourselves. Let's define a couple of pipes that get the job done.

For filtering, we'll have a pipe called PhoneFilterPipe. It works like the filter filter in Angular 1 in that it filters a collection of objects, matching properties within the objects. But, as opposed to filter, this pipe is specialized to filter Phone objects and we can use type annotations to make this explicit:

Since we're adding new code, it's a good idea to add some unit tests for it too. Here are a few tests for PhoneFilterPipe:

For sorting, we'll use a more generic pipe, just called OrderBy. It takes an array of objects, and a property to order the array by. It returns an array of the same type of thing it was given. In the implementation we copy the input array, sort the copy, and return it.

Here's a unit test for OrderByPipe as well:

We can now integrate these new pipes with our component. Before the pipes are available there, we need to declare them in the @Component decorator.

In the template we need to use the phoneFilter pipe instead of filter. No changes are needed for the orderBy

Now that the phone list is an Angular 2 component, there's one more neat trick we can apply to make its code a little bit simpler. Earlier, as we upgraded the Phones service, we needed to add a subscribe callback to the list response, which populated the phones array on the component. With Angular 2, we can instead just put the Observable itself on the component, and can skip the subscription callback:

This is made possible by the async pipe, which we can apply in the template. It knows how to turn an Observable to the (latest) value it has emitted:

That takes care of the phone list. Here's the updated unit test file for that component to complete the migration:

Before this test will run, we'll need to augment our Karma configuration so that component HTML templates are loaded properly. We didn't need them before when we were testing the controller in isolation, but our new test exercises the component as a whole, which includes the template.

Now we can start looking at our other controller, which is the one for the phone details. Rename phone_detail.controller.ts to PhoneDetail.ts, and set the contents as follows:

This is pretty similar to what we did with the phone list. The one new change here is the use of @Inject for the $routeParams dependency. It tells the Angular 2 injector what this dependency should map to. We have a dependency called $routeParams in the Angular 1 injector, where it is provided by the Angular 1 router. That is what we were already using when PhoneDetails was still an Angular 1 controller. The things is though, Angular 1 dependencies are not made automatically available to Angular 2 components, so if we were to run this now, it would not work.

We explicitly need to tell the UpgradeAdapter to upgrade $routeParams so that it is available for injection in Angular 2. We can do it in app.module.ts:

We now also need to convert the template of this component into Angular 2 syntax. Here is the new template in its entirety:

There are several notable changes here:

• We've removed the vm. prefix from all expressions.
• Just like we did in the phone list, we've replaced ng-src with property bindings for the standard src.
• We're using the property binding syntax around ng-class. Though Angular 2 does have a very similar ngClass as Angular 1 does, its value is not magically evaluated as an expression. In Angular 2 we always specify in the template when an attribute's value is a property expression, as opposed to a literal string.
• We've replaced ng-repeats with *ngFors.
• We've replaced ng-click with an event binding for the standard click.
• In all references to phone, we're using the elvis operator ?. for safe property navigation. We need it because when the component first loads, we don't have phone yet and the expressions will refer to a non-existing value. Unlike in Angular 1, Angular 2 expressions do not fail silently when we try to refer to properties on undefined objects. We need to be explicit about cases where this is expected.

In the module file we'll now register a pcPhoneDetail directive instead of a controller. The directive is a downgraded version of the PhoneDetail component.

In the router configuration in app.module.ts, we'll switch the details route to instantiate a component as well:

There's one additional step we need to take, which is to upgrade the checkmark filter that the template is using. We need an Angular 2 pipe instead of an Angular 1 filter.

While there is no upgrade method in the upgrade adapter for filters, we can just transform the filter function into a class that fulfills the contract for Angular 2 Pipes. The implementation is the same as before. It just comes in a different kind of package. While changing it, also rename the file to CheckmarkPipe.ts:

As we apply this change, we should also remove the registration of the filter from the core module file. The module's content becomes:

The unit test file for the filter also now becomes the unit test filter for the pipe. While we're still testing the same thing, we need to change how we set things up:

In the component we should now import and declare our newly created pipe:

With the phone detail component now migrated as well, we can go and migrate its unit tests too.

As we discussed earlier, Protractor tests should largely remain functional as we are making changes, since we're not really changing the user-visible behavior of the application. Now that we've migrated some components and their templates, however, there are a few changes we need to make. Apply the following replacements to scenarios.ts:

Switching To The Angular 2 Router And Bootstrap

At this point we've replaced all our Angular 1 application components with their Angular 2 counterparts. The application is still bootstrapped as a hybrid, but there isn't really any need for that anymore, and we can begin to pull out the last remnants of Angular 1.

There are just two more things to do: We need to switch the router to the Angular 2 one, and then bootstrap the app as a pure Angular 2 app.

Let's do the routing part first. Angular 2 comes with a shiny new router, but it isn't included by default. Just like we did with Http, we need to include it in index.html before the System.config() script first:

In the main app module we need to import a few things from the router module:

Angular 2 applications all come with a root component, which, among other things, is where we should plug in the router. We don't yet have such a root component, because our app is still managed as an Angular 1 app. Let's change this now and add an AppComponent class, which replaces the configure function in app.module.ts:

This is a component that plugs in to an <pc-app> element on the page, and has a simple template that only includes the router outlet component of the Angular router. This means that the component just renders the contents of the current route and nothing else. The @RouteConfig decorator defines the Angular 2 counterparts of our two routes. They refer directly to the two components.

We should put this <pc-app> element in the HTML so that the root component has something to attach to. It replaces the old Angular 1 ng-view directive:

In the PhoneDetail component we now need to change how the phone id parameter is received. There will be no more $routeParams injection available, because that comes from the Angular 1 router. Instead, what we have is a RouteParams object provided by the Angular 2 router. We use it to obtain the phoneId from the params:

We should also make the corresponding change in the unit test. We provide an instance of the RouteParams class instead of the $routeParams object:

With that, we're ready to switch the bootstrap method of the application from that of the UpgradeAdapter to the main Angular 2 bootstrap. Let's import it together with a couple of other things in app.module.ts

We'll now use the regular Angular 2 bootstrap function to bootstrap the app instead of using UpgradeAdapter. The first argument to bootstrap is the application's root component AppComponent, and the second is an array of the Angular 2 providers that we want to make available for injection. In that array we include all the things we have been registering with upgradeAdapter.addProvider until now, as well as the providers and directives of the router:

We are now running a pure Angular 2 application!

But there's actually one more cool thing we can do with the new router. We no longer have to hardcode the links to phone details from the phone list, because the Angular 2 router is able to generate them for us with its routerLink directive. We just need to refer to the route names we used in the @RouteConfig:

For this to work the directive just needs to be declared in the component:

To bring our Protractor test suite up to speed with the latest changes, there are a few remaining things we need to do. Firstly, now that we're no longer running Angular 1 at all, we should let Protractor know it should not be looking for one but instead find Angular 2 apps from the page. Add the following configuration option to protractor-conf.js:

Also, there are a couple of Protractor API calls in our test code that are using the Angular 1 $location service under the hood. As that service is no longer there, we need to replace those calls with ones that use WebDriver's generic URL APIs instead. The first of these is the redirection spec:

And the second is the phone links spec:

Now our E2E test suite is passing too, and we're ready to remove Angular 1 from the project!

Saying Goodbye to Angular 1

It is time to take off the training wheels and let our application begin its new life as a pure, shiny Angular 2 app. The remaining tasks all have to do with removing code - which of course is every programmer's favorite task!

First, rename app.module.ts to app.ts. It will no longer be setting up an Angular 1 module, so it doesn't really make sense to call it a module. Then remove all references to the UpgradeAdapter from app.ts. Also remove the Angular 1 bootstrap code, type definitions, and the imports of the core, phoneList, and phoneDetail modules. Instead import the PhoneList and PhoneDetail components directly - they are needed in the route configuration.

When you're done, this is what app.ts should look like:

You may also completely remove the following files. They are Angular 1 module configuration files and type definition files, and not required in Angular 2:

• app/js/core/core.module.ts (also app/js/core/upgrade_adapter.ts)
• app/js/phone_detail/phone_detail.module.ts
• app/js/phone_list/phone_list.module.ts
• test/test_helper.ts

Finally, from index.html and karma.conf.js, remove all references to Angular 1 scripts as well as jQuery. When you're done, this is what index.html should look like:

And this is what karma.conf.js should look like:

That is the last we'll see of Angular 1! It has served us well but now it's time to say goodbye.