- 1 Angular Interview Questions and Answers
- 1.1 What is [(ngModel)] used for?
- 1.2 What are the basic parts of an Angular application?
- 1.3 What are some advantages of using Angular framework for building web applications?
- 1.4 In Angular, how can you interact between Parent and Child components?
- 1.5 What is the sequence of Angular Lifecycle Hooks?
- 1.6 What is the main difference between constructor and ngOnInit?
- 1.7 How similar is AngularJS to Angular 2?
- 1.8 What is Transpiling in Angular?
- 1.9 What is AOT Compilation?
- 1.10 Optimizing an Angular 6 application for performance?
- 1.11 What are some important practices to secure an Angular application?
- 1.12 What’s the difference between unit testing and end-to-end testing?
In this Article, you’ll find top example most frequently asked for interview questions with answers you can refer to when seeking a new Angular developer to build your web applications. You’ll also get some practical advice on how to use these questions to reliably identify the best people for the job.
These interview questions are for Angular versions 2, 4, 5, 6 (‘Angular’) not angular JS.
Building Angular applications needs several different skills, and you would like the developers with the proper ones for your web app.
- Angular-specific skills – E.g. TypeScript, Building Single Page Applications
- Library/toolkit experience (Testing) – E.g. Jasmine and Karma
- Design skills – Performance optimization, Application security
Angular Interview Questions and Answers
Skill Requirements for Junior Angular Developers
- Foundational Angular knowledge (basics of angular js)
- Learning on the job (working hard)
- Following instructions and receiving feedback from Team Lead
- Thinking like a programmer
Write an example of a simple HTML document with some header information and page content. Requirement: Basic HTML skills
Answer: HTML documents are all different, but they follow a basic structure of head and body. Here you’re checking the candidate has a good grasp of HTML document structure and basic tags such as DOCTYPE, HTML, head, title, meta, body, h1, p, etc.
What are Single Page Applications? How do they work in Angular?
Answer: Single Page Applications (SPAs) are web applications that use only one HTML page. As the user interacts with the page, new content is dynamically updated on that master page. Navigation between pages happens without refreshing the whole page. Angular uses AJAX and to dynamically update HTML elements. Angular Routing can be used to make SPAs. The result is an application that feels more like a desktop app rather than a webpage
What is [(ngModel)] used for?
Answer: Two-way data binding.
What are the basic parts of an Angular application?
Answer: Modules, Component, Data Binding, Template, Directives, Dependency Injection, Services, Routing.
What are some advantages of using Angular framework for building web applications?
- Angular does lots of things for you under the hood. It saves time for developers by doing a lot of the work for them like writing tedious DOM manipulation tasks
- TypeScript and the Angular framework allow you to catch errors much earlier
- In many cases has faster performance than traditional web development techniques
- Can give web apps the feel of a desktop application
- It separates out the code of an application to make it easier for multiple developers to work on an app and easier to test
- A more consistent code base that’s easy to maintain
- Big developer community
In Angular, how can you interact between Parent and Child components?
Answer: When passing data from Parent to Child component, you can use the @Input decorator in the Child component. When passing data from Child to Parent component, you can use the @Output decorator in the Child component.
What is the sequence of Angular Lifecycle Hooks?
Answer: OnChange() – OnInit() – DoCheck() – AfterContentInit() – AfterContentChecked() – AfterViewInit() – AfterViewChecked() – OnDestroy()
What is the main difference between constructor and ngOnInit?
Answer: The constructor is a feature of the class itself, not Angular. The main difference is that Angular will launch ngOnInit after it has finished configuring the component. Meaning, it is a signal through which the @Input() and other banding properties and decorated properties are available in ngOnInit, but are not defined within the constructor by design.
What modules should you import in Angular to use [(ngModel)] and reactive forms?
Answer: FormsModule and Reactiveforms Module.
How similar is AngularJS to Angular 2?
Answer: Both are front-end frameworks maintained by Google, but Angular 2 is not a simple update of AngularJS, it is a new framework written from scratch. Updating an app from AngularJS to Angular 2 would require a complete rewrite of the code.
What is Transpiling in Angular?
What is AOT Compilation?
Answer: AOT refers to Ahead-of-time compilation. In Angular, it means that the code you write for your application is compiled at build time before the application is run in a browser. It’s an alternative to Just-in-time compilation, where the code is compiled just before it is run in the browser. AOT compilation can lead to better application performance.
Optimizing an Angular 6 application for performance?
Answer: There are many ways, some ideas include: AOT compilation, bundling and uglifying the application, tree shaking, lazy loading, separating dependencies and devDependencies, Using OnPush and TrackBy, removing unnecessary 3rd party libraries and import statements, avoid computing values within the template.
What are some important practices to secure an Angular application?
Answer: Some basic guidelines include:
- Check that all requests come from within your own web app and not external websites
- Sanitize all input data
- Use Angular template instead of DOM APIs
- Content Security Policies
- Validate all data with server-side code
- Use an offline template compiler
- Avoid including external URLs in your application
- Make JSON responses non-executable
- Keep all libraries and frameworks up-to-date
What’s the difference between unit testing and end-to-end testing?
Answer: Unit testing is a technique to test that isolated segments of code are functioning properly. End-to-end testing involves checking that entire sets of components to make sure they are working together properly and that the application is working as you would expect. End-to-end tests often simulate user interactions to test that an app is functioning as it should. Jasmine and Karma are all great testing tools.