Angular 7 interview questions and Answers
Angular 7 is a JavaScript web application development framework used to create Single Page Applications (SPAs). This is one of the foremost front-end development frameworks which has been regularly updated by the Angular team of Google. If you are scrolling on the web for Angular 7 interview questions, then this guide will gonna help you.
| Angular 7 | |
|---|---|
| What is the latest version of Angular? | Angular 11.0 released on 11th November 2020 |
| Angular is created by | |
| What language does Angular use? | TypeScript |
Most Frequently Asked Angular 7 interview questions
Here in this article, we will be listing frequently asked Angular 7 interview questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.
The main difference between Angular 7 and Angular 6 is -
| Differentiable parameters | Angular 7 | Angular 6 |
|---|---|---|
| Features | The main features that Angular 7 contains are- CLI prompts, Angular Material, Component Dev Kit (CDK), Virtual scrolling, and Application Performance Improvements, Angular Material, etc. | The main features that Angular 6 contained are- Angular CLI Workspaces, ng update, ng add, Angular Elements, Animations Performance Improvements, Bazel compiler, service worker safety, etc. |
| Prime focus | Angular 7 primarily focused on upgrading the existing features rather than publishing advanced level features. | Angular 6 primarily focused on adding new features and bring new extensible upgrades. |
| Angular Material and Components Dev Kit (CDK) | The Angular 7 framework has minor changes in the improvement of material design. | The Angular 6 framework has major changes in the improvement of material design. |
Angular 7 has new and advanced level features such as
- Modernized v7.0.2 CLI prompts
- Reflect- metadata poly-fill part for application performance
- Angular material and CDK ( Component Dev Kit)
- Virtual scrolling package
- Drag and Drop <@angular/cdk/drag-drop>
- Angular compatibility compiler (ngcc)
- angular Do-bootstrap
- improved error handling
- dependency updates etc
In addition to all these features, Angular 7 also provides Documentation updates which include Angular console, @angular/Fire, NativeScript, StackBlitz, and Bazel, platform- browser, etc.
Steps to update Angular 6 to Angular 7 are
- Remove deprecated features and components of RxJS 6 with the help of auto-update rules from rxjs-tslint.
- Install the tool by using command npm install –g rxjs-tslin
- From the root of your project run rxjs-5-to 6-migrate –p scr/tsconfig.app.json
- remove rxjs-compat library from rxjs-5-to 6-migrate –p scr/tsconfig.app.json
- Run command ng update @angular/cli@angular/core
Your Angular version gets updated to v7
UrlSegment is a modified feature of Angular 7 which is used to add a new interface. In other words, UrlSegment Interface feature represents URL segment, constructor, properties and methods which are present in UrlSegment class. Moreover, UrlSegement is one of the parts of URL, as it contains metric and path parameters which are associated and interlinked with the segment.
In Angular 7, templates are written with the help of HTML that contains Angular JS specification elements and attributes. The main role of Angular 7 is to combine the templates which ultimately control the dynamic view that is visible to the users in the browsers.
Structural directive
The main function of the structural directive is to shape and re-shape the HTML layout, and DOM’s structure. The modification and customization of HTML layout are done by adding, removing and manipulating the selected HTML elements.
Attribute directives
The attribute directive has its own layout view and styles because it has a single component on a host element but it supports multiple directives.
Angular 7 has two core dependencies namely RxJS and TypeScript
- RxJS 6.3 – Angular 7 framework uses RxJS version 6.3.
- TypeScript- Angular 7 framework uses TypeScript version 3.1
In order to set headers for every request in Angular 7, HTMLHttpRequest is used. There is a number of benefits such as testability features, types request, request and response interception, observable APIs and streamlined error handling that is associated with, XMLHttpRequest.
The utility functions provided by Angular are:
- map() : Used to map values of different data types
- filter() : Used for filtering streams
- concat() : Used to concatenate multiple strings
- merge(): Used to recursively descend into object properties in the source copy, while forming a deep copy of the same.
In Angular, during each navigation route, the Router sends navigation events through the Router Events property.
Here is the list of events range from when the navigation starts and ends too many points in between.
- NavigationStart
- RouteConfigLoadEnd
- GuardsCheckStart
- ActivationStart
- GuardsCheckEnd
- ResolveStart
- ActivationEnd
- NavigationEnd
export class AppComponent {
constructor(private router: Router) {
}
ngOnInit() {
this.router.events
.pipe(filter(event => event instanceof NavigationEnd))
.subscribe(() => {
...
});
}
}
Here are the reasons to use an AOT compiler in Angular:
- Faster rendering: Using the AOT compiler, browsers can download a pre-compiled version of the application. This ensures that the browser can render the application immediately using executable code without having to wait for the whole compilation.
- Less asynchronous requests: Using inline external HTML templates and CSS style sheets within the application, the compiler eliminates separate ajax requests for those specific resource files.
- Reduced Angular framework download size: There's no need to download the Angular compiler if the app is already compiled. This is very advantageous and efficient as the compiler is almost half the size of Angular, so, not having to add that increases the application payload dramatically.
- Optimized Error Handling: Detecting existing template errors and reporting template binding errors during the building step before users can see.
- Enhanced Security: Compilation of HTML templates and other components into JS files before client-side rendering. This reduces the scope for risky JS evaluation or injection attacks. The AOT compiler the HTML templates and other components into JS files before they are served to the client. With no templates to read and no risky client-side JavaScript or HTML evaluation, there are fewer opportunities for injection attacks.
The Router.navigate is used to specify a root URL through relative navigation. Here’s a function using the above to navigate through different articles in Angular:
gotoDetails(articleId: any) {
this.router.navigate(['/blog/', blogId]);
}
The command, ng generate service [service name] generates a service in Angular.
An API stands for Application Programming Interface. It is basically a set of rules and tools for building software applications. In AngularJS, the Global API is a combination of global functions written in Javascript which are used for tasks like comparing/iterating objects or converting data.