Angular 7 Interview Questions & Answers: Master the Framework

Prepare for your Angular 7 interview with this comprehensive guide covering fundamental and advanced concepts. This resource provides detailed answers to frequently asked Angular 7 interview questions, exploring key differences between Angular 7 and AngularJS, the core components of the Angular framework (modules, components, templates, services), and its architecture. We delve into structural and attribute directives, NgModules (`declarations`, `providers`, `imports`), and new features introduced in Angular 7 (e.g., `ng update`, virtual scrolling). This guide also explores advanced topics like NativeScript and StackBlitz, equipping you with the knowledge needed to confidently answer interview questions and showcase your Angular expertise.

Top Angular 7 Interview Questions and Answers

What is Angular 7 and How Does it Differ from AngularJS?

Angular 7 is a version of the Angular framework. AngularJS (Angular 1.x) was the original version. Angular 7 is a complete rewrite and significant improvement, featuring two-way data binding and enhancements like the Angular CLI, improved performance, and support for new libraries. It's not just an update; it's a fundamentally different architecture.

What is the Angular Framework?

Angular is a TypeScript-based, open-source web framework used for building modern web, mobile, and desktop applications. Key features include declarative templates, dependency injection, and comprehensive tooling that simplifies development.

AngularJS vs. Angular

AngularJS Angular
Based on MVC architecture. Component-based architecture.
Uses JavaScript. Uses TypeScript.
Controller-based approach. Component-based UI approach.
Not inherently mobile-friendly. Mobile-friendly.
SEO optimization can be challenging. Easier SEO optimization.

Structural vs. Attribute Directives

Structural directives modify the DOM layout by adding or removing elements (e.g., *ngFor, *ngIf). Attribute directives modify the appearance or behavior of an existing DOM element (e.g., ngStyle, ngClass).

`declarations`, `providers`, and `imports` in NgModule

  • `declarations`: Lists components, directives, and pipes that belong to the module. These are only available within the module or modules that import it.
  • `providers`: Specifies services that are available for dependency injection within the module. Lazy-loaded modules have their own injectors.
  • `imports`: Lists external modules whose exported components, directives, pipes, and services are needed within this module.

Key Components of Angular

  • Components: The fundamental building blocks, managing a view (HTML template) and its data.
  • Modules: Organize the application into logical blocks of functionality.
  • Templates: HTML views that display data and interact with components.
  • Services: Provide reusable functionality across the application.
  • Metadata: Decorators (@Component, @Directive, @Injectable) that provide additional information to Angular about classes.

Angular Architecture Overview

Angular applications are built using modules (NgModule), which provide a context for components. Components manage views (templates) and interact with services via dependency injection. Angular's modular design promotes organization and reusability.

A typical AppModule created by the Angular CLI includes:

  • declarations: Lists the app's components.
  • imports: Includes BrowserModule (essential for browser-based apps).
  • providers: Initially empty; services are added here.
  • bootstrap: Specifies the root component (AppComponent).

Updating from Angular 6 to Angular 7

Use the command: ng update @angular/cli @angular/core

UrlSegment Interface

The UrlSegment interface represents a single segment of a URL path, containing a path and parameters.

`ngDoBootstrap`

ngDoBootstrap is a lifecycle hook introduced in Angular that allows for custom bootstrapping logic, overriding the default bootstrapping process.

Directives in Angular 7

Directives enhance existing DOM elements or components. They add behavior or modify appearance.

Example Directive

import { Directive, ElementRef, Input } from '@angular/core';

@Directive({ selector: '[myHighlight]' })
export class HighlightDirective {
    constructor(el: ElementRef) {
        el.nativeElement.style.backgroundColor = 'green';
    }
}

Components in Angular 7

Components are directives with templates, forming the building blocks of an Angular application's UI. Each component manages a specific part of the view.

Example Component

import { Component } from '@angular/core';

@Component({
    selector: 'my-app',
    template: `
        <p>Angular 7 Interview Questions & Answers:  Master the Framework</p>
        <p>Learn Angular</p>
    `
})
export class AppComponent {
    title: string = 'Welcome to Angular!';
}

Component vs. Directive

Component Directive
Directive with a template. Adds behavior to an element.
Uses @Component decorator. Uses @Directive decorator.
One per DOM element. Multiple per DOM element.
Creates UI widgets. Modifies existing elements.

Templates in Angular 7

Templates are HTML views that are bound to a component's data. They can be defined inline within the component or in a separate HTML file.

Modules in Angular 7

Modules are logical containers for related components, services, and directives. They enhance application organization and structure.

Example Module (app.module.ts)

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';

@NgModule({
    imports: [BrowserModule],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

New Features in Angular 7

  • Improved styling and theming.
  • Virtual scrolling support.
  • Drag-and-drop functionality.
  • Automatic updates for Material Design libraries.
  • Enhanced error handling for @Output properties.
  • Support for Node v10.
  • Angular Console.
  • @angular/fire (Firebase integration).
  • NativeScript support.

Angular 7: Additional Features and Tools

Cross-Platform Development with Angular 7

Angular 7, through frameworks like NativeScript, enables the creation of single projects that can be built for both web and mobile platforms (iOS and Android). This simplifies development and reduces the need for separate codebases.

StackBlitz 2.0

StackBlitz 2.0 is a significant update to the online IDE for Angular projects, incorporating the Angular Language Service. This improvement provides enhanced features and functionality within the browser-based development environment. This offers a streamlined workflow for developing and testing Angular applications, especially useful for quick prototyping and collaboration.