First 10 Angular Interview Questions and Answers in the year - 2022 - USMTECHWORLD.

Some of the Frequently Asked Questions in Angular:-
1. What is angular and why used?
2. What is the difference between Angular and Angularjs
3. Advantage of using Angular?
4. What are the different types of DataBinding in Angular?
5. What is string interpolation?
6. What is AOT Compilation ?
7. What are the advantages of AOT?
8. Difference between AOT Compiler and JIT Compiler in Angular?
9. What are the Life Cycle hooks in Angular?
10.Difference between Angular Expression and Javascript Expression?

1. What is angular and why used??

Answer:
Angular is client side Javascript open source framework developed by google.It allows developers to build web applications for mobile and desktop users.The main technologies involved in the development of angular are HTML,CSS and JAVASCRIPT,TYPESCRIPT.

2.What is the difference between Angular and Angularjs

Answer:
Angular


Angularjs

3.Advantage of using Angular

Answer:

4.What are the different types of DataBinding in Angular?

Answer:
There are four types of databinding in Angular.


String Interpolation

String interpolation in a one way databinding technique to bind data from typescript (ts) file to view file(html).It uses double curly braces. For example,
{{Name}} {{Email}}
if you type anything in the typescript code of name, that will be reflected in the html file. usercomponent.ts
export class usercomponent{ Name="Hello USMTECHWORLD" }
usercomponent.html
DisplayName: {{Name}}

Property Binding

It is one way databinding technique. For eg:- App.component.html:

App.component.ts
export class app{ title="This is property binding example" }
Whenever we modify the value of title in the app.component.ts file, it automatically gets reflected in the view.This is one way databinding technique.

Event Binding

Event binding is used to handle events raised from DOM elements like button click,mouse move,mouse up etc.When button is clicked the specific method is called. For example,

            <button (click)="samplemethod()"><button>

Two way DataBinding

First we recap one way databinding, whatever we change in ts code will be reflected in the view,but reverse is not possible.But in Two way databinding whenever we change anything in the view , it should be reflected in the typescript code. The best example of two way databinding is ngModel. It syncs value from UI to Property as well as from Property to UI.This is called two way databinding. The syntax for ngModel directive is [()] also known as banana box syntax. for example,
usercomponent.html

    <div>
    Loginname: <input type="text" [(ngModel)]="username">
{{username}} <div> export class user{ username:string="Helloworld!!!" }
Whenever we change username in the textbox will be reflected in the Loginname section.Similarly when we change username in the typescript code like username:string="USMTECHWORLD", it gets reflected in the view.This is Two way databinding.

5.What is String Interpolation?

Answer:
String interpolation means dynamic data changing technique,if you change data in component file the output will be resulted in front end i.e (HTML) SAMPLE.TS file:-

            import {Component} from '@angular/core';  
@Component(  
  {selector: 'samplepage',  
 templateUrl: 'samplepagecomponent.component.html'})  
export class samplepagecomponent {  
    username: string = 'USMTECHWORLD STRING INTERPOLATION';  
}  
SAMPLEPAGE.HTML:
<p>username:{{username}}<p>

6.What is AOT Compilation?

Answer:
AOT stands for AHEAD OF TIME Compiler.It is used to convert our HTML code and Typescript code into Javascript code during its build phase itself. This makes application to render faster in the browser. The order of AOT compiler:-

7.What are the advantages of AOT Compiler?

Answer:
Here the application is compiled before running inside the browser.So browser loads the executable code and render the application quickly which leads to faster rendering. The developers can find errors in compilation phase itself which greatly helps to reduce errors. The AOT compiler adds HTML and templates into JS files before they run in browser

8.Difference between AOT Compiler and JIT Compiler?

Answer:
AOT COMPILER


JIT COMPILER

9.What are the Life Cycle hooks in Angular?

Answer:
The Order of Life Cycle Hooks in Angular

10.Difference between Angular Expression and Javascript Expression?

Answer:
Angular Expression: In Angular we can write javascript inside HTML,all expressions in angular are scoped locally means it cannot be accessed outside the local scope. For example,

    @component({
selector:'SampleApp',
template:'<h1> message <h1>'
})
export class SampleApp
{
message:string="HELLO USMTECHWORLD";
}
From the above code it can be understood that message variable can be used within the scope of SampleApp class. The syntax for angular expression is as follows, {{data}}
Here data is assigned from typescript code.

Javascript Expressions: Javascript expression cannot handle null or undefined.For eg:- let strage; document.getElementbyi('userage').innerHTML=strage;