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AngularJS按需动态加载template和controller?

Angular is nothing but an open-source web application framework. It is being led by the Angular Team at Google and also by a community of individuals and corporations. It is based on TypeScript.Angular is a complete rewrite from the same team that had built AngularJS. It can be used as the frontend of the MEAN stack, which consists of the MongoDB database, Express.js web application server framework, Angular itself (or AngularJS), and the Node.js server runtime environment.

we plan to migrate to Angular 1, and we'll finish out the decade on React

But you can still run into strange race conditions where the browser displays stale data depending on if some other unrelated code has caused a digest update to run after the buggy code or not.

Converting Angular components into Svelte is largely a mechanical process. For the most part, each Angular template feature has a direct corollary in Svelte. Some things are simpler and some are more complex but overall it's pretty easy to do.

We don't use "attribute directives" much which makes things easier.

Directives like ng-if="info.report.revenue" sort of work in Angular if info.report is undefined, in that the ng-if becomes false. But the Svelte equivalent {#if info.report.revenue} throws an error. For now we're using lodash get in places where we need to and looking forward to Svelte support for optional chaining.

Embedding Svelte inside Angular is pretty easy, for the most part. I wrote a function that would take in a Svelte component and generate an Angular controller class.

It's really helpful that Svelte stores are easy to use in plain JS. We can change a state store over completely to Svelte and make the Angular components subscribe to that store as well without needing to maintain and sync 2 copies of the state.

The advantage of ngOnChanges() is that we get all the changes at once if the component has several @Input()s. However, if we have a single @Input() a setter is probably the better approach.

A View is a fundamental building block of the application UI. It is the smallest grouping of Elements which are created and destroyed together.

an Angular application is a tree of components

Content is what is passed as children usually to be projected at some <ng-content> element of a component. View is the template of the current component. The view is initialized after the content and ngAfterViewInit() is therefore called after ngAfterContentInit().

In Angular CLI 6 this command has been removed, and it will not come back. Instead there is a new concept called Builders.With the new Angular CLI you can customize the build process by defining your own builders as well as using one of the builders provided by the community.

In Angular CLI 1.x (Angular 5) you had ng eject command for this, which was ejecting the whole underlying webpack configuration and allowing you to modify it as you please.

this.txtQueryChanged .debounceTime(1000) // wait 1 sec after the last event before emitting last event .distinctUntilChanged() // only emit if value is different from previous value .subscribe(model => { this.txtQuery = model;

With Angular 2 we can debounce using RxJS operator debounceTime() on a form control's valueChanges observable:

I think Svelte's approach where it replaces component instances with the component markup is vastly superior to Angular and the other frameworks. It gives the developer more control over what the DOM structure looks like at runtime—which means better performance and fewer CSS headaches, and also allows the developer to create very powerful recursive components.

being able to compose multiple components' functionality via decoration (not creating new "combo" components or something) is more elegant, and something I wish React had.

The whole point of directives is composability. First: you can apply a directive to any component, even components included from other libraries. Second: you can apply multiple directives to the same component. Directives are decorators, so it's not the same thing.

The let keyword declares a template input variable that you reference within the template. The input variables in this example are hero, i, and odd. The parser translates let hero, let i, and let odd into variables named let-hero, let-i, and let-odd.

SPAs are incredibly common, popularised by client-side web frameworks like Angular, React and Vue.js.

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I'm super stoked about Vue.js though...I'm kind of over Angular at this point since it left a bad taste in my mouth last year (it's a much larger framework and the 'official' build system isn't even being used anymore by programmers)

I'm doing a newer project in Vue.js because it looks much lighter than Angular and just awesome all around

Been there, done that. Vue.js takes the best ideas form Angular (and some from React), without putting you in ZoneAwareError hell.

@angular-react/core

But like its usual in the case of Observable-based APIs, FRP techniques can help easily implement many use cases that would otherwise be rather hard to implement such as: pre-save the form in the background at each valid state, or even invalid (for example storing the invalid value in a cookie for later use) typical desktop features like undo/redo

This is why this is called template-driven forms, because both validation and binding are all setup in a declarative way at the level of the template.

You are probably wondering what we gained here. On the surface there is already a big gain: We can now unit test the form validation logic

Then inject it inside a test by calling TestBed.get() with the service class as the argument. it('should use ValueService', () => { service = TestBed.get(ValueService); expect(service.getValue()).toBe('real value'); });

However, you almost always inject service into application classes using Angular dependency injection and you should have tests that reflect that usage pattern. Angular testing utilities make it easy to investigate how injected services behave.

We can even remove the AuthService import if we want, there really is no dependency on anything else. The LoginComponent is tested in isolation:

That’s not very isolated but also not too much to ask for in this scenario. However imagine if LoginComponent required a number of other dependencies in order to run, we would need to know the inner workings of a number of other classes just to test our LoginComponent. This results in Tight Coupling and our tests being very Brittle, i.e. likely to break easily. For example if the AuthService changed how it stored the token, from localStorage to cookies then the LoginComponent test would break since it would still be setting the token via localStorage.

Mocking localStorage is optional, but without mocking getComputedStyle your test won’t run, as Angular checks in which browser it executes. We need to fake it.

Or inside the beforeEach() if you prefer to inject the service as part of your setup. beforeEach(() => { TestBed.configureTestingModule({ providers: [ValueService] }); service = TestBed.get(ValueService); });

This is known as the entry file.

When we use ng new the Angular CLI creates a new workspace for us.In our Angular workspace we are going to have two projects:A library projectThis is the library of components and services that we want to provide. This is the code that we could publish to npm for example.An application projectThis will be a test harness for our library. Sometimes this application is used as documentation and example usage of the library.

When we’ve generated the library (ng generate library tvmaze ) Angular CLI modified the tsconfig.json in the root of our project by adding tvmaze to the paths entry.

Why is that useful? It enables such service to be tree-shaken (removed form the production bundle if not used)

Then it gets the native element of the compiled HTML (the HTML rendered by the component).

We use an async before each. The purpose of the async is to let all the possible asynchronous code to finish before continuing.

The CLI takes care of Jasmine and karma configuration for you.

The custom id is persistent. The extractor tool does not change it when the translatable text changes. Therefore, you do not need to update the translation. This approach makes maintenance easier

The Angular extraction tool preserves both the meaning and the description in the translation source file to facilitate contextually-specific translations, but only the combination of meaning and text message are used to generate the specific id of a translation. If you have two similar text messages with different meanings, they are extracted separately. If you have two similar text messages with different descriptions (not different meanings), then they are extracted only once

You need to build and deploy a separate version of the app for each supported language

The CLI imports the locale data for you when you use the parameter --configuration with ng serve and ng build

To define a class as a service in Angular, use the @Injectable() decorator to provide the metadata that allows Angular to inject it into a component as a dependency. Similarly, use the @Injectable() decorator to indicate that a component or other class (such as another service, a pipe, or an NgModule) has a dependency.

retire our default home page that is built with a Jade view, and instead use an Angular view

how it uses zones

In general, add providers to the root module so that the same instance of a service is available everywhere.

you get a new instance of the service with each new instance of that component

Component classes should be lean. They don't fetch data from the server, validate user input, or log directly to the console. They delegate such tasks to services.

While a component is technically a directive, components are so distinctive and central to Angular applications that this architectural overview separates components from directives.

other metadata decorators

Change: collapse to uib-collapse.

function(context, locals)