Are you planning to sit for an interview for the post of Angular Developer? Well, preparing yourself with these Angular interview questions is best.

If you are a JavaScript developer, you might know the Angular framework for front-end development. It has become one of the most in-demand skills for developers in the present world.

However, it can be a bit difficult to have a good understanding of the Angular framework. In such a case, being prepared for anything an interviewer can throw at you is essential. From directives to frameworks, it will help you ace an interview and get the job that can take your career to a new level.

We have sorted some of the most popular Angular interview questions for which you should be prepared to get your dream job.

What is Angular Expression? How are they different than JavaScript Expression?

Angular Expression is a code snippet that coders place in {{ expression }} binding. The significant difference between Angular and JavaScript Expressions are:

  • It is easy to use filters before displaying format data.
  • Evaluation is forgiving to undefined and null instead of JavaScript undefined that generates ReferenceError and TypeError.
  • Evaluated against a scope object.
  • Angular Expressions include exceptions, conditionals, and loops.

Explain data binding.

Data binding is considered one of the most influential and essential features that can establish a connection between components and DOM. It is simple to define the process of interactive applications without worrying about pulling and pushing the templates and components. Several types of data binding are used in Angular, such as

  • Property binding,
  • Two-way data binding,
  • Event binding, and
  • String interpolation.

Give a glimpse into different lifecycle hooks of Angular.

The hooks of the Angular lifecycle are popular when checking triggers and phase changes during the entire duration of a specific phase. The lifecycle component includes the Constructor, which is divided into four major parts: ngOchanges, ngOnInit, ngDoCheck, and ngOnDestroy. ngOchanges are also dining into ngAfterViewInit, ngAfterContentInit, ngAfterViewChecked, and ngAfterContentChecked.

  • ngOnchanges( ) – When one (or more) input properties are changed in the components, this method is called. The previous and current values of the properties are received in the hook – SimpleChanges.
  • ngOnInit( ) – It comes after ngOchanges to initialize sets input properties and components.
  • ngDoCheck( ) – It comes at the third stage to act and detect changes that are impossible with Angular. One can quickly implement a change detection algorithm using this hook.
  • ngAfterContentInit( ) – Another hook is to responded after one get content projects in component.
  • ngAfterContentChecked( ) – Next is ngAfterContentChecked that is called after every subsequent ngDoCheck and ngAftercontentInit responding after the content projected.
  • ngAfterViewInit( ) – The next hook to call is ngAfterViewInit to respond to the child component’s view after the component’s view is checked.
  • ngOnDestroy( ) – It helps detach event handlers and clean up the code before Angular destroys the component.

What is the difference between AOT and JIT in Angular?

Many may get confused between AOT and JIT compiler in Angular, and hence it is essential to know the basics:

  • Ahead-of-Time (AOT) compiler compiles the code on the server at the build time. At the same time, the Just-in-Time (JIT) compiler is at the run-time in the browser for the application.
  • AOT is ideal for production mode, whereas JIT is for development mode that can compile code in Angular project.
  • AOT compilation includes ng serve and ng build commands, whereas JIT compilation includes ng serve and ng build CLI commands.
  • AOT can reduce bundle size for faster rendering, whereas JIT comes with debugging and implementing major features to map files.

Explain RxJS.

Reactive Extensions for JavaScript (RxJS) uses observables allowing developers to perform reactive programming. The aim is to compose callback-based code or asynchronous operations using the RxJS framework in Angular. It can help in streaming data to subscribers emitting values from publishers. If you are not using Angular, other programming languages such as Python and Java can use observables using reactive code.

Deep dive into distinct types of Angular filters.

Angular uses a filter to show the users formatting the expression value that can be added to templates, directives, services, and controllers. One can create personalized filters based on the requirements allowing users to organize data based on criteria. After the pipe symbol ( | ), filters are placed in the expression. The primary filters used in Angular are:

  • number – To convert the value into a string
  • currency – Converting numbers to currency format
  • json – Converting any object to JSON string
  • date – Converting it in any date format
  • limitTo – Limit the array or string to particular strings or elements
  • orderBy – Arranges array in the expression
  • uppercase – Converting a string into uppercase
  • lowercase – Converting a string into the lowercase
  • filter – Select subset from given array

Define bootstrapping.

Bootstrapping is a way to start or initialize the application in Angular, whether automatic or manual. Let us help you understand it in a better way:

  • Automatic bootstrapping is included when adding ng-app directives on the tag if required. Angular compiles the DOM and is associated with module finding ng-app directive.
  • Manual bootstrapping is to initialize the Angular app and offer control to the developers to perform significant operations and tasks to compile the page.

Throw some light on Angular directives.

When it comes to Angular directives, there are three significant kinds such as:

  • Attribute – Using this, one can change the behavior and appearance of elements, another directive, and components. It uses ngStyle and ngClass as the attributes of elements.
  • Components – It consists of templates that can define a single user interface using CSS styles, TypeScript code, and HTML template. It is usually decorated with @ symbol giving an angular compiler to replace it with the component templates.
  • Structural – It changes the view structure to hide or show some data using different directives such as ngIf directives.


These are the essential questions and answers usually asked in Angular interviews. It will help you prepare for the interview, ace it, and get your dream job.

If you are done with this, know more about AngularJS.