Angular Dependency Injection Tokens
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Questions and Answers

What are the major features of Angular?

Declarative templates, dependency injection, end to end tooling

Describe Angular as a framework.

Angular is a completely revived component-based framework where an application is a tree of individual components.

What is the purpose of directives in Angular?

Directives add behavior to an existing DOM element or component instance.

Where can you store a component's template in Angular?

<p>Inline using the template property or in a separate HTML file linked with @Component decorator's templateUrl property.</p> Signup and view all the answers

What is the purpose of NgModule decorator in Angular?

<p>To define logical boundaries in the application and divide it into separate modules.</p> Signup and view all the answers

How does Angular divide the functionality of an application?

<p>By separating the application into different modules.</p> Signup and view all the answers

What is the purpose of ngOnInit in Angular?

<p>To indicate that Angular is done creating the component and for initialization/declaration tasks.</p> Signup and view all the answers

What is the main responsibility of the Constructor in Angular?

<p>To initialize class members and set up Dependency Injection.</p> Signup and view all the answers

Why is it advised not to perform actual 'work' in the constructor of an Angular class?

<p>To keep the constructor focused on initialization and use ngOnInit for actual component setup.</p> Signup and view all the answers

What is the significance of services in Angular applications?

<p>Services provide common functionality to various modules, promoting separation of concerns and modularity.</p> Signup and view all the answers

Explain the purpose of ElementInjector hierarchies in Angular.

<p>ElementInjector hierarchies are created for DOM elements matching Angular components or directives, facilitating dependency injection.</p> Signup and view all the answers

What is the default method in a class that is executed upon instantiation in Angular?

<p>Constructor.</p> Signup and view all the answers

Why is it recommended to use services for common functionality in Angular?

<p>To promote better separation of concerns and modularity by extracting common functionality out of components.</p> Signup and view all the answers

When does Angular call the ngOnInit lifecycle hook?

<p>After Angular is done creating the component.</p> Signup and view all the answers

What is the role of the NullInjector in Angular dependency injection?

<p>To throw an error when dependencies are not found, except when @Optional() decorator is used.</p> Signup and view all the answers

How does Angular handle the registration of services in an application?

<p>Angular creates a root injector where services are registered via the @Injectable annotation.</p> Signup and view all the answers

What is the name of the Angular module that you bootstrap to launch the application?

<p>AppModule</p> Signup and view all the answers

What is the major advantage of using HttpClient in Angular applications?

<p>HttpClient.get() method returns an Observable of typed HttpResponse.</p> Signup and view all the answers

How can you handle errors returned from HttpClient in an Angular component?

<p>By passing an error object as a second callback to the subscribe() method.</p> Signup and view all the answers

What is RxJS used for in Angular applications?

<p>RxJS is used for composing asynchronous and callback-based code in a functional, reactive style using Observables.</p> Signup and view all the answers

What should you do to begin receiving values from an Observable instance?

<p>Subscribe to it by calling the subscribe() method.</p> Signup and view all the answers

What is the purpose of an Observer in RxJS?

<p>An Observer is a consumer of push-based notifications delivered by an Observable.</p> Signup and view all the answers

What is the difference between Promise and Observable?

<p>Promises can only handle a single future value, while Observables can handle multiple values over time.</p> Signup and view all the answers

What is multi-casting in the context of Observables?

<p>Multi-casting is the practice of broadcasting to a list of multiple subscribers in a single execution.</p> Signup and view all the answers

How can you handle errors in Observables using an error callback?

<p>By specifying an error callback on the observer.</p> Signup and view all the answers

What method can accept callback function definitions for next, error, and complete handlers in Observables?

<p>subscribe() method</p> Signup and view all the answers

What is the purpose of the animation transition function in Angular?

<p>To specify the changes that occur between one state and another over a period of time.</p> Signup and view all the answers

How can you inject dynamic HTML, Style, Script, and Url using DomSanitizer?

<p>Using DomSanitizer to inject the dynamic content.</p> Signup and view all the answers

What are some key differences in how dependency injection works between AngularJS and Angular?

<p>Dependency injection is a common component in both, but the implementation differs.</p> Signup and view all the answers

How can you enable Ivy in an existing Angular project?

<p>By adding the enableIvy option in the angularCompilerOptions in the project's tsconfig.app.json.</p> Signup and view all the answers

What are some features you can expect with Ivy preview in Angular?

<p>Faster AOT compilation and the ability to opt for a preview version of Ivy.</p> Signup and view all the answers

How can you add a Web Worker in an Angular application?

<p>By using the ng generate web-worker app command.</p> Signup and view all the answers

What is the purpose of an App Shell in Angular?

<p>To render a portion of the application via a route at build time for faster initial display.</p> Signup and view all the answers

What is the significance of capitalization conventions in Angular?

<p>To distinguish the names of various types within the framework.</p> Signup and view all the answers

What are class field decorators in Angular?

<p>Decorators declared immediately before a field in a class definition.</p> Signup and view all the answers

What is a DI token in Angular?

<p>A lookup token associated with a dependency provider in the dependency injection system.</p> Signup and view all the answers

What determines the type of compilation (JIT or AOT) when running ng build or ng serve commands?

<p>The value of the aot property in the build configuration specified in angular.json.</p> Signup and view all the answers

What error is generated if arrow functions are still used in Angular?

<p>An error node is generated in place of the function.</p> Signup and view all the answers

What does the RouterOutlet directive do?

<p>It acts as a placeholder in the template where the router should display components.</p> Signup and view all the answers

What kind of functions cannot be used to assign values to decorator properties in Angular?

<p>Arrow functions or lambda functions.</p> Signup and view all the answers

How can you access the current RouterState in an Angular application?

<p>You can access it using the Router service and the routerState property.</p> Signup and view all the answers

What is the purpose of the RouterLink directive in Angular?

<p>It gives the router control over anchor tags for navigation paths.</p> Signup and view all the answers

What process does the compiler perform when it evaluates an expression during collection?

<p>Folding.</p> Signup and view all the answers

What are macros supported by the AOT compiler in Angular?

<p>Macros in the form of functions or static methods that return an expression.</p> Signup and view all the answers

Explain the purpose of RouterLinkActive directive.

<p>It toggles CSS classes for active RouterLink bindings based on the current RouterState.</p> Signup and view all the answers

How can you enable binding expression validation in Angular?

<p>By adding the compiler option fullTemplateTypeCheck in the tsconfig.json.</p> Signup and view all the answers

How can you define a wildcard route in Angular?

<p>A wildcard route has a path consisting of two asterisks to match every URL.</p> Signup and view all the answers

How can you implement animation in an Angular project?

<p>By using Angular's state() function to define different states and associated styles.</p> Signup and view all the answers

What is ActivatedRoute used for in Angular?

<p>It contains information about a route associated with a component and can be used to traverse the router state tree.</p> Signup and view all the answers

How should a router be configured with route definitions?

<p>You configure the router with routes via the RouterModule.forRoot() method.</p> Signup and view all the answers

What is the purpose of the style() function in Angular animations?

<p>To define a set of styles to associate with a given state name.</p> Signup and view all the answers

What does Angular Animations provide for single page web applications?

<p>A powerful way to implement sophisticated and compelling animations.</p> Signup and view all the answers

What is the purpose of Ahead-of-Time (AOT) compilation in Angular?

<p>It compiles the Angular app at build time, making it the default starting in Angular 9.</p> Signup and view all the answers

How can you define a state transition in Angular animations?

<p>By specifying a unique name and associated styles using state() and style() functions.</p> Signup and view all the answers

How can custom elements functionality be implemented in Angular?

<p>You can use NgElement and WithProperties types exported from @angular/elements.</p> Signup and view all the answers

What utility functions are provided by the RxJS library for working with observables?

<p>The RxJS library provides utility functions for creating and working with observables.</p> Signup and view all the answers

What is the purpose of Http Interceptors in Angular?

<p>Http Interceptors inspect and transform HTTP requests and responses.</p> Signup and view all the answers

How can you access elements directly in the view in Angular?

<p>You can use the @ViewChild directive.</p> Signup and view all the answers

What is the role of a Subject in RxJS?

<p>Subjects are a special type of Observable that allows multicasting.</p> Signup and view all the answers

How can you report missing translations in Angular?

<p>You can configure Angular compiler to show a warning or an error for missing translations.</p> Signup and view all the answers

What is the purpose of Bazel tool in Angular?

<p>Bazel tool provides advantages like bypassing the Angular CLI builder and running Bazel directly.</p> Signup and view all the answers

What is the context in which an Angular application runs?

<p>A platform is the context in which an Angular application runs, such as a web browser or an operating system.</p> Signup and view all the answers

How does Angular DSL differ from normal HTML?

<p>Angular DSL is a specialized syntax on top of normal HTML that Angular uses.</p> Signup and view all the answers

What happens if custom ids for text messages are not unique?

<p>If custom ids are not unique, the translation units will contain the translation of the first message with that id for all subsequent messages with the same id.</p> Signup and view all the answers

How can you use Angular as a platform-independent framework?

<p>By utilizing the @angular/platform-* packages, Angular can be used as a platform-independent framework.</p> Signup and view all the answers

What is the key advantage of using a Subject over a plain Observable in RxJS?

<p>Subjects are multicast, while plain Observables are unicast.</p> Signup and view all the answers

What is the purpose of the AsyncPipe in Angular?

<p>The AsyncPipe subscribes to an observable or promise and returns the latest value it has emitted.</p> Signup and view all the answers

When should you use inline template and when should you use an external template file in Angular components?

<p>Inline template is usually used for small portions of code, while external template files are preferred for bigger views.</p> Signup and view all the answers

How does Angular handle the innerHtml property binding to prevent XSS vulnerability?

<p>Angular recognizes the value as unsafe and automatically sanitizes it, removing the script tag but keeping safe content.</p> Signup and view all the answers

What is interpolation in Angular and how is it represented?

<p>Interpolation is a special syntax represented by double curly braces {{}} that Angular converts into property binding.</p> Signup and view all the answers

What is a template expression in Angular and how is it used?

<p>A template expression produces a value similar to any Javascript expression and is used in property binding or interpolation.</p> Signup and view all the answers

What is a template statement in Angular and how is it different from a template expression?

<p>A template statement responds to an event raised by a binding target, such as a button click, and is represented by (event)=&quot;statement&quot;.</p> Signup and view all the answers

What is the purpose of pipes in Angular and how are they used?

<p>Pipes are simple functions that transform data input into a desired output using template expressions.</p> Signup and view all the answers

What are the three categories in which binding types in Angular can be grouped?

<p>Binding types can be grouped into three categories distinguished by the direction of data flow.</p> Signup and view all the answers

How can a pipe be parameterized in Angular?

<p>A pipe can be parameterized by declaring the pipe name with a colon ( : ) followed by the parameter value.</p> Signup and view all the answers

What is the default behavior of the Angular CLI when generating components with templates?

<p>By default, the Angular CLI generates components with a template file.</p> Signup and view all the answers

What is the purpose of the safe navigation operator in Angular?

<p>The safe navigation operator guards against null and undefined values in property paths, preventing null reference errors.</p> Signup and view all the answers

How does the safe navigation operator help in accessing nested properties in Angular?

<p>It allows accessing nested properties without worrying about null reference errors.</p> Signup and view all the answers

When using the JIT compiler in Angular, how can you specify the warning level?

<p>By adding the 'MissingTranslationStrategy' property in the compiler config at bootstrap.</p> Signup and view all the answers

In Angular, if you use the AOT compiler, where should you make changes to the configuration?

<p>Changes should be made in the configurations section of the angular.json file.</p> Signup and view all the answers

Is the @Injectable() decorator mandatory on every service class in Angular?

<p>No, the @Injectable() decorator is not strictly required if the class has other Angular decorators.</p> Signup and view all the answers

What is the alternative name for the safe navigation operator in Angular?

<p>Elvis Operator</p> Signup and view all the answers

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