Introduction to Angular JS Interview Questions and Answers

If you are looking for at is related to Angular JS, you need to prepare for the 2022 Angular JS Interview Questions. Though every Angular JS Interview is different and the job scope is also different, we can help you with the top Angular JS Interview Questions and Answers, which will help you take the leap and get your success in Angular JS. So we have designed the most common Angular JS Interview Questions and Answers to help you get success in your interview.

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Below is the list of 2022 Angular JS Interview Questions updated for 2022. These questions are divided into two parts.

Part 1 – Angular JS Interview Questions (Basic)

This first part covers basic Angular JS Interview Questions and Answers

Q1. Explain Angular JS in brief?

Answer:
A Structural framework that lets you use HTML as your language for templates. Also, it allows you to extend the Syntax of HTML. It provides flexibility to avoid writing hundreds of initialization codes just to get started.
Google started to work with Angular JS in 2009.
It is data binding and performs or showcases all the output within the Browser. We can also call it a JavaScript framework which can be added with the <Script> tag in the HTML pages. It provides options to the developers to write an application for the client side using JavaScript.

Q2. Name directives in AngularJS that will define what variable value to be used.

Answer:
Using Directive, we can define the input time as Text; the entered Text could be Email, Name, etc. Angular JS uses ng-model.
Use ng-model in Angular JS Code:
Input Code:

<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"></script>
<body>
<div ng-app="myApp" ng-controller="myCtrl">
Institute Name: <input ng-model="name">
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
$scope.name = "EduCBA";
});
</script>
<p>That's how we can use this input directive as Text input.</p>
</body>
</html>

Let us move to the following Angular JS Interview Questions.

Q3. Explain the code to enable the double-click button in Angular JS?

Answer:
ng-dblclick allows for specifying custom behavior on a double-click event on the web pages. It can be used as an attribute of the HTML element.
Using the following procedure, we can create a sample code of a double-click event using AngularJS.
ng-model has bound as a Textbox, and then the double click button is attached with ng-dblclick & we have written ‘Hello ‘+name.
Here Hello is a string and name defined as the variable containing input value as TextBox.
This button – “Double Click for EduCBA,” will work when you double-click on it.
Input Code:

<!doctype html>
<html ng-app>
<head>
<script src="angular.min.js"></script>
</head>
<body>
Name:
<input ng-model="name" type="text" />
<button ng-dblclick="Msg='Hello '+name">
Double Click for EduCBA
</button>
</br>
<h3>
Please double click - EduCBA
</h3>
</body>
</html>

Q4. What do “routes” do in Angular JS?

Answer:
It enables the creation of different-different URLs for the different content in the application. Angular js route allows users to bookmark content of different URLs for the other content. These such bookmark URLs are the route in AngularJS.
The value of a Number, JavaScript, or String in Angular JS is a simple object & this should belong to Angular JS.
The values are used as configuration injected into controllers, services, or factories. Adding a parameter can inject values into the Angular JS controller function, having named the same value.

Q5. Explain some Unique features of AngularJS?

Answer:
Registering Callbacks is not required in Angular JS. This feature makes Angular JS code much more straightforward to debug.
The applications created using Angular JS never influence the DOM (Document Object Model).
Angular JS helps to transfer the data to and from the UI; it also helps to eliminate issues like validating a form, validation error display, etc.

Q6. List all types of Custom directives in Angular JS?

Answer:
Following are the Custom directives in Angular JS:

Element directives: This Directive works when the matching element is confronted.
CSS class directives: It starts working when the same CSS style matches.
Comment directives: When a matching comment is found, it gets activated.
Attribute directives: Attribute directives come into the picture when matching/same directive is confronted.

Q7. Explain different types of bootstrapping in AngularJS?

Answer:
Starting or initializing the application is called Bootstrapping. Angular JS has two types of bootstrapping.

Automatic Bootstrapping: Adding the ng-app at the root of an application. After finding the ng-app angular js loads, the associated module with it, and then the compilation of DMO happens.
Manual Bootstrapping: To get more control over the initialization of your angular app, we use manual bootstrapping. It provides control over how and when to start the app. It is useful when another operation is performed before waking up the Angular JS and compilation of the page.

Let us move to the following Angular JS Interview Questions.

Q8. Explain any Angular JS service using the code?

Answer:
Services are the objects or functions used to carry out specific tasks.
A developer in Angular JS can build it. Angular JS developers can define their services. They can explain the service’s name and factory function by registering it. Also, almost 30 to 35 inbuilt services are available for instant use. $timeout is one of the Angular JS services.
$timeout service changes the value in a specified number of milliseconds. This service helps change the deal after the predefined time limit.
Input Code:

<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"></script>
<body>
<div ng-app="myApp" ng-controller="myCtrl">
<p>EduCBA code will change this header will change after 3 seconds:</p>
<h1>{{myHeader}}</h1>
</div>
<p>The $timeout service works after a specified number of milliseconds.</p>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope, $timeout) {
$scope.myHeader = "Hello EduCBA!";
$timeout(function () {
$scope.myHeader = "How are you today?";
}, 3000);
});
</script>
</body>
</html>

“This code will change the value to default after 3 seconds.”

Q9. Explain all the Security features in AngularJS.

Answer:
Angular JS provides built-in protections. Refer to the following security features.
It prevents Cross-site scripting. It is a hacking technique where a hacker can send a request form and get confidential or private information quickly.
It also prevents injection attacks on HTML.
It prevents XSRF (Cross-site request forgery) protection for server-side communication. Angular JS handled it by the “Auth token” mechanism. Whenever users log in for the first time, it sends a user id and password to the server, returning an Auth token. This authorized token does the authentication in all future transactions.

Q10. Explain the Syntax to show the entered password using Angular JS.

Answer:
Using the below code, the Developer can switch the visibility of the password to the user.
Input Code:

<!-- Password field -->
Password: <input type="password" value="EduCBA" id="myInput">
<!-- An element to switch between password visibility -->
<input type="checkbox" onclick="myFunction()">Show Password

Part 2 – Angular JS Interview Questions (Advanced)

Let us now have a look at the advanced Angular JS Interview Questions.

11. Explain the different directives in Angular JS?

Answer:
These directives are only used when a developer wishes to extend the behavior of HTML and DOM elements. These have a prefix as –ng that tells the compiler that specified behavior is to be attached to that DOM element. The built-in directives that AngularJS has are as below:
•ngBind,
•ngModel
•ngClass
•ngApp
•ngInit
•ngRepeat

User-defined directives can also be used in applications and with controllers and services. Let us get to know the above directives in detail

ngApp: This Directive is important in Angular JS. This Directive marks the starting of Angular Application to Angular JS HTML compiler, like the main() function in any compile-time language like C++, Java, etc. If this Directive is not written first and other directives are, then an error would be thrown.
ngInit: It is a directive used to initialize application data variables. These can be used in the blocks where they are declared. It is local to the ng app and can be a collection of values.
ngModel: This directive is a model to be used in HTML controls like <input type=’text’/>. It provides a binding behavior with the values. Hence it is used in data binding.
ngBind: It binds model variables with HTML controls and tags. A user can only see output values.
ngRepeat: As the name suggests, it is used to repeat HTML statements. It works similarly to a loop in languages like Java or PHP.

12. How will you boot Angular JS?

Answer:
Whenever the DOM Content Loaded event is called, Angular JS initializes. Another way for this initialization process is when an angular.js script is downloaded, and the document is ready. This is when a ngApp directive is called, which acts as the root of compilation and tells apart the Angular part from the DOM. The following happens when ngApp is called. The module that is associated with the Directive will be loaded. An application injector must be created, and the DOM starting from the Directive should be compiled. This entire process is known as auto bootstrapping.

13. What is jQLite? Write a small code to explain.

Answer:
It is a query that is built directly in Angular JS. It is known to be a subset of jQuery. jQLite provides all the features of jQuery. jQuery can be used with Angular JS by simply loading the jQuery library beforehand.

<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="angular.min.js"></script>
</head>
<body ng-app="app">
<div ng-controller="mainCtrl">
<input type="text" id="txtName" value="Debanjana Mukherjee" />
<button type="button" ng-click="clickme()">Click me</button>
</div>
<script type="text/javascript">
var app = angular.module('app', []);
app.controller("mainCtrl", function($scope, $element) {
$scope.clickme = function() {
var elem = angular.element(document.querySelector('#txtName'));
console.log(elem.val()) // console the value of textbox
};
});
</script>
</body>
</html>

14. Explain the $scope object in Angular JS. Explain with a small snippet.

Answer:
It is an object that binds view with a controller. Data is accessed through the $scope object when a controller is called. The DOM object and controller can use this object as a communication means. This object can have both data as well as functions. Every Angular JS application has a $rootscope, created on the view and has the ng-app Directive.
The scope object helps in providing APIs to observe any model. It is a mediator between the view and controller; it can be nested. But being nested does not give access to all properties. The properties can be limited, and the nested scope can either have a child or isolated scope. It also provides a context against the expression that is to be evaluated.

<html>
<head>
<title>Angular JS Scope</title>
<script src="angular.js"></script>
<\head>
<body ng-app="myapp">
<h2>AngularJS - Scope Inheritance</h2>
<div ng-controller="ParentController">
<div ng-controller="firstChildController">
<div ng-controller="secondChildController">
<p>Parent Name:{{parentName}}</p>
<p>First Child Name:{{level1name}}</p>
<p>Second Child Name:{{level2name}}</p>
</div>
</div>
</div> In the above example, we have three controllers parent Controller, firstChildControllerand secondChildController. All three controllers are attached to DOM elements in a nested way. The expressions will be associated with the current scope and search for the parent scope until the rotoscope is reached.

15. What is a SPA in Angular JS?

Answer:
Single Page Applications are dynamic pages that load a single HTML page and later update that page as the user goes ahead and interacts with the application. This does not mean that this dynamic behavior impacts the server side. These pages are loaded on the client side. SPAs use AJAX and HTML for creating responsive web applications.

As the application is a single page, once it delivers to the Browser, it does not require to be loaded repeatedly as the user will navigate to various parts of the application. This helps in faster navigation and efficient working of the web page.

16. What is dependency injection?

Answer:
When objects are passed as dependencies and which, as a result, remove hard-coded dependencies, then the objects are to be injected. The need for dependency injection comes when we separate the creation and consumption of dependency. The use of this feature helps the user to change dependencies whenever required. Also, mock objects can be injected for testing purposes.

17. What happens when a double-click event is called?

Answer:
Using this event, the double-click can be customized as per requirement. ng-dblclick can be used as an attribute in HTML. The process to customize it is by adding an external Angular.js file. Once this external file is downloaded from the Angular JS official site, the Developer can add the file to the head section of the HTML file.

18. Explain different ways by which a directive can be invoked.

Answer:
A directive can be invoked in four ways:

1) As an attribute – <time directive></time>
2) As a class- <time class =”directive: exp></time>
3) As an element- <new directive></new directive>
4) As comment- <!– directive: my-directive expression –>

19. What are filters?

Answer:
Filters help select a subset of items from an array and return a new array. They can be used to display filtered items based on the specified criteria. The different filters provided by Angular JS are currency, date, limitTo, lowercase, number, etc.

20. What is the difference between prefix $ and $$?

Answer:
When the name of an object is prefixed with $, it is public, and when it is prefixed with $$, the thing is private.

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