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Top 35 Angular 4 Interview Questions and Answers

Girdhar Gopal Singh  Print   10 min read  
18 Feb 2020
30 Jun 2020
Intermediate
1.15K Views

Angular 4 is a Javascript-based web application framework to build apps in HTML, TypeScript, and JavaScript. Angular 4 was released in the year 2017 on March. Angular 4 mainly offers built-in features for Animation, HTTP services, and materials. It supports cross-platform and mainly used to develop Single Page Applications in web application development. Today this is an essential part for many organizations and if you want to build your career in this field, and then you have to make yourself as a professional expert so that you can crack the interview and get a good job in the industry. Here, we are providing the top 35 questions and answers for Angular 4 to prepare yourself for the interview.

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Top 20 Angular Interview Questions and Answers

  1. What is Angular 4?

    angular 4 is a Javascript framework for building apps in HTML, TypeScript and JavaScript. It has built-in features for HTTP service, animation and materials.

  2. What would be the best free IDE for Angularjs?

    Sublime Text, Atoms, Visual Code, etc.

  3. What is Unit Testing in Angular 4?

    Private testing or unit testing is basically used to test the system’s components. It is the process to test small separate pieces of code. But when any unit testing depends on any of the external resources like networks, databases, and APIs, then it would not come under unit test.

  4. What is binding?

    The binding process in Angular 4 is the process of establishing synchronization between the View and Model Components which are different layers in the application.

  5. Describe different types of binding in Angular 4?

    The different kinds of binding in Angular 4 are Two Way Binding, Event Binding, and Property Binding. These data bindings are the important components of Angular. Event Binding is the process of updating values of a variable or attribute from the View Component layer to the Model Component Layer. Property Binding is the way of updating the values of a variable in Model Component and displaying it in the View Component. Two Way Binding is the combination of Property Binding and Event Binding features.

  6. What is dependency injection in Angular 4?

    Dependency injection describes an important application design pattern which is used to enhance the effectiveness and modularity of an application. This is mainly a coding pattern where class requests for dependencies from the external or third-party sources rather than creating it itself.

  7. What are the Modules in Angular 4?

    A module is defined as a file where all the Components, Directives, Pipes and Services are interlinked and grouped together to make it a proper and perfect working application for Angular. Every Angular app has a root module that will be defined inside app.module.ts (a TypeScript file format). To define a module in Angular 4, NgModule is being used.

  8. What are the @NgModule Metadata Properties?

    It is a method which takes a single metadata object to tell Angular how to compile the application.

    Essential factors of Metadata:
    • Imports

    • Exports

    • Schemas

    • Providers

    • Declarations

    • entryComponents

    • bootstrap

    • id

  9. Why Angular 4 is faster from its previous version?

    Angular 4 is faster when compared to its previous version. Here are a few versions given below:

    • It decreases the size and of generated code bundle up to 60%.

    • It is backwards compatible.

    • The animation section shifted to a different package.

  10. Describe the features of Angular 4?

    Angular 4 has several new features. Most of the changes have been implemented to the background of the current version, not in the core functionality of coding. Some of the features are:

    • Dynamic Components

    • TypeScript Compatibility

    • Source Maps for Templates

    • AOT Compilation

    • Router ParamMap

    • Flat ES Modules

    • Angular Universal

    • Smaller and Quick

    • Revamped *nglf and *ng

    • Animations Package

  11. Describe ElementRef in Angular 4?

    ElementRef is a class used for abstraction. The Class structure mainly holds the native elements and ElementRef is used to access the native elements.

  12. What is deep linking in Angular 4?

    Deep Linking mainly takes a specific page directly without searching and traversing application from the landing page of the website. It will ultimately help in generating and getting indexes so that such specific links can easily be searched by search engines. In Angular 4, deep linking use # for supports.

  13. How to install Angular 4?

    There are so many different ways to install Angular 4:

    • Install Angular CLI

    • Create a project

    • Serve the application

  14. Describe the use of TypeScript in Angular 4?

    It is a native language for Angular 4 Development. TypeScript has Design-tome support system for tooling and Type Safety. It is mainly a superset of JavaScript.

  15. What are the different types of component decorators in Angular 4?

    There are basically 4 types of component decorators in Angular 4:

    • Class Decorators

    • Parameter Decorators: used for parameters inside the class constructors

    • Property decorators: used for properties inside classes

    • Method Decorators: used for methods inside classes

  16. Explain Eager loading in Angular 4?

    There are 3 types of loading – eager loading, lazy loading and preloading. Eager loading is the module format which has to import into the Angular 4 application by introducing the metadata of @ngmodule decorator. It is helpful for small size angular applications.

  17. What is Routing?

    Routing is the process to apply routes on different components in Angular 4 so that it can display the content of the component mainly in Single Page Applications. The functionality of router enables the users to navigate from one work to other tasks while performing multiple functionalities at a time.

  18. Difference between Angular 4 and Angular 5?

    Angular 4 is fast and more compact whereas Angular 5 is widely used in building optimized applications. Angular 4 is Angular Universal and Angular 5 is Angular universal as well as State transfer. Angular 4 uses TypseScript 2.1 and TypeScript 2.2 but Angular 5 is using TypeScript 2.5.

  19. Difference between JavaScript and ECMAScript?

    Javascript: It is a programming language which is designed for web pages. Developed by Netscape and Sun, it is used to enhance web page s with interactive and dynamic features.

    ECMAScript: It is an abbreviated form of European Computer Manufacturer’s Association which is mainly used in scripting languages like JavaScript, Jscript etc.

  20. What is Guard in Angular 4?

    In case o Angular 4, when functionalities, logic as well as code are executed before loading of a route is called as Guards. It checks the route access, any new features in a module, child route access and provides response to the user of any unsaved changes.

  21. What is Lazy Loading?

    It is well known method that is used for loading the JavaScript components asynchronously while a particular routing feature is activated.

  22. What is use of CanActivate?

    CanActivate is the feature in Angular Interface that is focused on the security. It helps the user to login for any application during the routing of a page.

  23. What is JWT Interceptor?

    It is used to intercept Http requests from the application when any users log in to add a JWT in the Authorization header.

  24. What is JIT?

    JIT or Just-in Time compilation which is also known as Dynamic translation or run-time compilation is used to execute computer code during the compilation of code in angular 4 or you can say during the run-time of a program, precisely, prior to the execution.

  25. What is AOT?

    AOT or Ahead of Time compilation is used to convert your code during the build time before it loads on the browser. This will give a scope to faster rendering in the browser.

  26. What is Transpiling?

    Transpiler that is run on TypeScript is used in Angular 4 to compile all the TypeScript code created in the development process and convert them into JavaScript for interpretation into the browser.

  27. What is the use of Angular Material?

    It is a user-interface component library to help in developing attractive, functional and stable web pages as well as applications while maintaining the best practices involved such as browser portability, graceful degradation and device independence.

  28. What does CDK mean?

    CDK or Component Dev Kit is a set of tools to implement common interaction patterns throughout the code.

  29. What is Flex?

    Flex is a layout or a component engine that will allow you to easily create Flexbox based page layouts with a specific set of directives available for your template.

  30. What are Angular 4 Providers?

    These are the injectors that inject the objects by the providers. There are different types of Angular 4 providers – Class provider, Factory Provider, Value Provider and Alias Provider.

  31. Difference between Angular and Angular JS?

    Angular JS is the first version of the Angular. Angular CLI tool is used to generate Angular components. Angular JS is a client-side framework that works with JavaScript, still supported but not compatible with Angular. Angular JS is the old version and Angular is the newest version.

  32. How to create a new component in Angular 4 through CLI?

  33. To create a new component by using CLI:
     
    Open Project Directory
    
    Run any one of the mentioned below syntax:
     
    ng component name OR
    ng generate component componentname
    
  34. How to upgrade from Angular 2 to Angular 4

    You only have to update the tsconfig.json and package.json files. Some minor changes may need as per the requirement of the project types.

  35. What is embedded view in Angular 4?

    Embedded view is a hosting component that used to define a template.

  36. Explain reducers in Angular 4?

    A reducer is a function to specify how a specific state changes in response to any event or action.

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