Angular Ionic Interview Questions
JAVASCRIPT
What is hoisting?
Its mechanism
Variable and function declarations are moved to the top of their scope before code execution.
console.log(x) //undefined
var x = 10
console.log(x) // print 10
console.log(y+z) //reference error
let y = 10
const z = 10
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Difference between let and var?
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What are let, var, and const in javascript?
let - block scoped, redeclared not supported in same scope
const - block scoped, redeclared or redesigned are not supported
var - function scoped, redeclared and redesigned are supported
Difference of == and === in javascript?
== - compare the value
=== - compare the value and data type
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Implicit Type Coercion?
automatically convert the value from one datatype to another datatype
var a = 10
var b = "mani"
a+b //"10mani"
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Javascript is dynamically typed language
type of variable are checked while compile-time
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What is NaN? - Not a number
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Passed by value and passed by reference?
Primitive data types are passed by value
Non-primitive data types are passed by reference
Passed by value in primitive data types only
a = 10 //memory reference 101
b = a //b memory reference 102, it will copy the value from a and stored in new memory
Passed by reference in non-primitive data types only
var obj1 = {id:1, name: "mani"}
var obj2 = obj1
These are used same memory reference
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Purpose of "this" keyword in javascript? - this will refer the current object variables
var obj = {
name: "vivek",
getName: function(){
console.log(this.name);
}
}
obj.getName();
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What is call(), apply() and bind() methods? - predefined methods
call() method allows an object to use the method (function) of another object.
call() accept argument
function saySomething(message){
return this.name + " is " + message;
}
var person4 = {name: "John"};
saySomething.call(person4, "awesome");
// Returns "John is awesome"
apply() - its same like call but its accept the argument are array
bind() - This method returns a new function, where the value of “this” keyword will be bound to the owner object, which is provided as a parameter.
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Scopes in Javascript?
There are three types of scopes in JS:
Global Scope
Local or Function Scope
Block Scope
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Expansion of DOM? - Document object model
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What is arrow function?
its introduced ES6 verions
val r = function(a,b){
return a+b
}
var arrowab = (a,b) => a+b;
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What is Event listening in javascript?
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What is onload() and purpose?
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Javascript Sequence:
function showData(data){
document.getElementById("demo").innerHtml = data;
}
function addData(num1, num2){
let sum = num1 + num2;
showData(sum);
}
addData(2,3);
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What is SCSS? - Sassy Cascading Style Sheets
ANGULAR
Types of observables in rxjs angular?
1) Subject
2) Behaviour subject
3) Replay subject
4) AsyncSubject
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What is Subject?
Subject is special type of observables
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Difference of Subject and Observable?
observable support single casting
subject support multiple casting
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Types of subjects:
Subject
BehaviourSubject - We can set initial/default value and remember previous data
ReplaySubject - Remember custom number of previous data
AsyncSubject - Its will print only final data while complete it
Angular Lifecycle hooks?
ngOnChanges
ngOnInit
ngDoCheck
ngAfterViewInit
ngAfterViewChecked
ngAfterContentInit (ng-content)
ngAfterContentChecked
ngOnDestroy
Eg:
parent ngOnInit
parent ngOnChanges
parent ngondocheck
content ngonint
content ngonchanges
content ngondocheck
parent ngonAfterContentInit
parent ngOnAfterContentChecked
child ngOnChanges
child ngoninit
child ngondocheck
child ngonAfterViewInit
child ngOnAfterViewChecked
content ngOnAfterViewInit
content ngOnAfterViewChecked
parent ngOnAfterViewInit
parent ngOnAfterViewChecked
parent ngOnDestroy
content ngOnDestroy
child ngOnDestroy
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What is Angular Binding?
String Interpolation - One way data binding
Property Binding - [] - One way data binding in html widgets
Event Binding - () - One Way data binding from html to ts
([ngModel]) - Two way data binding
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What is directive and types of directives?
component directives - <ng-app></ng-app>
structure directives - ngIf, nfFor
Attribute directive - ngModel, ngClass, ngStyle
custom directive - change element of dom style and behaviour
@Directive({
selector : "[test]"
})
class BGClass {}
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What is pipe?
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What are the default pipes in angular?
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What are difference between ngFor, ngForOf?
<div *ngFor="let item of Items">
<template [ngFor]="let item of items">
<template ngFor let-item="variable" [ngForOf]="items">
ngForOf - type safe - allow generic type
ngFor - not type safe
ngFor is not iterate the ng-container, ng-content directly
so we use ngForOf
ngFor is structural directive, its replace to ng-repeat
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Different of observable vs promise?
Observable is lazy, multiple value can passed, can be cancelled
Promise is eager, single value emitting, not lazy, cann't cancelled,
const obs = new Observable.create(
observer =>{
observer.next(),
observer.error(e),
observer.complete()
})
obs.subscribe(x => console.log(x))
const promise = new Promise((resolve, reject)=>{
resolve("test")
reject("error")
})
promise.then(x => console.log(x))
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What is HttpInterceptor?
intercept(req: HttpRequest, next: HttpHandler)
req.url
req.clone({
headers: req.headers.set()
});
next.handle()
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What is difference of Authorization and Authentication?
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What is Authguard?
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What is difference of canActivated, canLoad in angular?
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IONIC
ionic lifecycle hooks
ngOnInit
ionViewWillEnter
ionViewDidEnter
ionViewWillLeave
ionViewDidLeave
ngOnDestroy
Eg: page 1 -> page 2
ngOnInit
ionViewWillEnter
ionViewDidEnter
ngOnInit - 2
ionViewWillLeave
ionViewWillEnter - 2
ionViewDidEnter - 2
ionViewDidLeave - 1
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The syntax for Angular project creation?
ng new projectName
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Ionic Project Creation?
ionic start projectName black/tabs --type=ionic-angular --capacitor/cordova
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What is capacitor?
Capacitor is support progressive web app (Elector, android, ios)
Cordova for web application
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How to create custom cordova plugin?
Using Plugman framework
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Ios Certificates:
Development,
AdHoc,
Enterprise,
AppStore
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ionic 4 folder structure?
e2e
node_modules
platforms
plugins
src
resources
www
angular.json
config.xml
package.json
ionic.config.json
src
app
assets
environments
theme
global.scss
index.html
main.ts
karma.config.js
polyfills.ts
test.ts
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Difference between ionic 3 vs ionic 4?
karma.conf.js - Ionic 4
main.ts - Ionic 4
polyfills.ts - Ionic 4
angular.json - Ionic 4
ionViewDidLoad, ionViewCanEnter, ionViewCanLeave is removed in ionic 4
Angular router is used instead of navcontroller in ionic 4
promised used for alertController in ionic 4 with async and await
async is used to return the promise
await is used wait for the promise
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Type of forms in angular?
Template-driven Form
Reactive Form
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Form Module:
ngForm, ngModel, ngSubmit
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Reactive Form Module:
FormGroup,
FromControlName
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What is Injectable annotation in angular?
@Injectable({
providedIn:"root"
})
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How to update the appstore build after change bundle id?
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What is lazy loading?
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What is canload in authguard?
canload - prevent the unauthorized user to entire module of app, used in lazy loading
canactivate - is used to prevent an unauthorized user, used in eager loading
canload - is not download the chunk.js file, its hidden difference
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Syntax of lazy loading?
const routes: Routers =[{
path : "login",
loadChildren()=> import(../LoginModule).then(m => m.loginModule)
component: LoginComponent
}]
AppModule.forRoute(routes)
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How to install the pod in ios?
sudo gem install cocoapods
pod install
pod deintegrate
pod repo update
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What is interceptor?
HttpInterceptor is interface, it has intercept method with httprequest, httphandler
req.clone(setHeader())
next.handle(req)
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Usecase of handle data in onload?
onload="init(data)"
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Angular lifecycle, Which lifecycle hooks triggered first?
ngOnInit
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Ionic.config.xml purpose?
name of app, integration is cordova/capacitor, type = ionic-angular
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Ionic 4 project structure?
e2e, src, platform, resources, plugins, www, node_modules
src, app, environments, theme, assets, karma.config.js, main.ts, global.scss, index.html
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Internal testing vs test flight in ionic app?
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How to integrate third-party library in ios?
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How to load 1000 data without lacking in ionic - collection-repeat directive
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How to know platform type in ionic
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How to do test cases in ionic?
How to create a custom plugin in Cordova?
What is the difference between cordova vs capacitor?
What is the difference between ionic 3 and ionic 4?
What is lazy loading?
What are the lifecycle hooks ionic 4?
How to do a list of data in ionic?
What is the difference between ionic prepare and ionic build?
How to deploy the android and ios build?
What is the difference between async and await?
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