
AngularJS Interview Questions and Answers
Question 1
Explain component life cycle in Angular?
Explain component life cycle in Angular?
In Angular component life cycle in Angular goes through following stages.
Create
Render
Create and render children
Check for bound data changes and re-render
Destroy
Question 2
List the types of Data Binding supported by Angular5?
String Interpolation
Property Binding
Event Binding
Two-way-binding
Question 3
What are the new features of Angular 2?
- Universal server rendering- It is the library which is used to make building universal apps a smooth experience. It is an important feature of Angular 2.
- A mobile toolkit- It provides all the mobile toolkit and techniques to build high-performance mobile applications. The web applications which are developed using the mobile toolkit can be loaded on any device with or without internet connection which is a great advantage.
A command line interface-it can generate components, routes, services, and pipes with the help of commands.
Question 4
How do you define the transition between two states in angular?
Question 5
What is the difference between observable and promises?
Observable is a more powerful way of handling HTTP asynchronous requests. Whereas, A promise handles a single event when an asynchronous operation completes or fails.
An observable is like a stream which allows passing zero or more events where the callback is called for each event. Whereas, A promise eventually calls the success or failed callback even when you don’t need the notification or the result it provides anymore.
Observable works with multiple values for a particular time. Whereas, Promises works with and even returns a single value at a time.
Observables can be canceled. Whereas, Promises cannot be canceled.
Observable supports map, filter, reduce and similar operators. Whereas, Promises have more readable codes with try/catch and async/await.
In observable, one operator ‘retry’ can be used to retry whenever needed. Whereas, Promises cannot be retried. A promise should have access to the original function that returned the promise in order to have a retry capability.
Question 6
What is ECMAScript?
Question 7
List the key components of Angular 2?
Module – This is used to break the application into the logical pieces of the program code and each piece of code or module is designed to perform a single and unique task.
Component – This is used to bring the modules together.
Templates – This is used to define the Views of an Angular JS application.
Metadata – This is used to add more data to an Angular JS application.
Service – This component is used to develop the components, which can be used to share in the entire application.
Question 8
Explain the component directory structure of angular4?
module.ts- in this, the angular module is declared. @NgModule decorator is used which initializes the different aspects of angular applications. AppComponent is also declared in it.
components.ts- it simply defines the components in angular and this is the place where the app-root sector is also defined. A title attribute is also declared in the component.
component.html- it is the template file of the application which represents the visual parts of our components.
Question 9
Explain property binding or one way binding in Angular js?
Interpolation can be used to define a value, as long as the value being defined is a string.
Wrapping brackets around the element property and binding it to the component property is the most common type of property binding.
The third way is by adding “bind” before the element property.
Question 10
What’s new in Angular 5?
Angular 5 supports RxJS 5.5 which has new features like Pipeable Operators
A build tool to make the js bundles (files) lighter
Ahead of Time (AOT) is updated to be on by default
Events like ActivationStart and ActivationEnd are introduced in Router
Question 11
Explain the concept of scope hierarchy.?
Question 12
Explain what a digest cycle is in AngularJS?
Question 13
Briefly describe how Angular digest cycle work?
Question 14
Explain what is directive and Mention what are the different types of Directive?
Different types of directives are
Element directives
Attribute directives
CSS class directives
Comment directives