AngularJS interviews Question

Certainly! Here are 50 AngularJS interview questions along with their answers and examples:

1. What is AngularJS?

AngularJS is an open-source JavaScript framework developed by Google for building dynamic web applications. It simplifies front-end development by providing tools and structures for building single-page applications (SPAs).

2. What is data binding in AngularJS?

Data binding is a two-way synchronization between the model and view in AngularJS. When data in the model changes, the view is automatically updated, and vice versa.

3. Explain the difference between one-way and two-way data binding.

One-way data binding: Data flows in one direction, from the model to the view or vice versa.

Two-way data binding: Data flows in both directions, allowing automatic updates in both the model and the view.

4. What is an AngularJS directive?

Directives are special markers on DOM elements that AngularJS uses to attach behavior to them. Examples include ng-model, ng-repeat, and ng-if.

5. What is dependency injection in AngularJS?

Dependency injection is a design pattern used in AngularJS to manage dependencies and provide objects that a component needs. It helps make components more modular and testable.

6. Explain the concept of controllers in AngularJS.

Controllers are JavaScript functions that manage the data and behavior of a part of the application. They are responsible for setting up the initial state and handling user interactions.

7. How do you define a controller in AngularJS?

app.controller('MyController', function($scope) {

    // Controller logic here

});

8. What is ng-repeat, and how is it used?

ng-repeat is a directive used for iterating over a collection (e.g., an array) and rendering a template for each item in the collection.

<ul>

    <li ng-repeat="item in items">{{ item }}</li>

</ul>

9. Explain AngularJS services and give an example.

Services in AngularJS are singletons that can be injected into various parts of your application. They are used to share data and functionality across different components. For example:

javascript

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app.service('MyService', function() {

    this.getData = function() {

        return ["Item 1", "Item 2", "Item 3"];

    };

});

10. What is a filter in AngularJS? Provide an example.

Filters are used for formatting the data displayed to the user. For example:

<p>{{ someDate | date: 'yyyy-MM-dd' }}</p>

11. Explain the concept of routing in AngularJS.

Routing allows you to build single-page applications with different views or pages. The ngRoute module provides routing capabilities in AngularJS.

12. How do you define routes in AngularJS?

You can define routes using the $routeProvider in the configuration phase of your app:

app.config(function($routeProvider) {

    $routeProvider

        .when('/', {

            templateUrl: 'home.html',

            controller: 'HomeController'

        })

        .when('/about', {

            templateUrl: 'about.html',

            controller: 'AboutController'

        })

        .otherwise({ redirectTo: '/' });

});

13. What is AngularJS' digest cycle?

The digest cycle is a process in AngularJS that checks for changes in the model and updates the view accordingly. It's responsible for keeping the data in sync between the model and the view.

14. Explain the concept of scope in AngularJS.

Scope is an object that refers to the model. It acts as a bridge between the controller and the view, allowing data to flow between them.

15. What is a directive in AngularJS? Provide some built-in directives.

A directive is a behavior or transformation applied to DOM elements. Built-in directives include ng-model, ng-repeat, ng-if, ng-show, and ng-hide.

16. Explain ng-model and give an example.

ng-model is used for two-way data binding. It binds an input element's value to a property on the scope.

<input type="text" ng-model="name">

17. What is the difference between ng-if and ng-show/ng-hide?

ng-if: Removes or recreates the DOM element based on a condition.

ng-show/ng-hide: Hides or shows the DOM element using CSS.

18. What is an AngularJS factory? Provide an example.

A factory is a function that returns an object. It is often used to create services.

app.factory('MathService', function() {

    var factory = {};

    factory.add = function(a, b) {

        return a + b;

    };

    return factory;

});

18. What is the purpose of the $http service in AngularJS?

The $http service is used to make HTTP requests to a server, allowing you to retrieve or send data asynchronously.

20. Explain how to make an HTTP GET request using $http.

app.controller('MyController', function($scope, $http) {

    $http.get('/api/data')

        .then(function(response) {

            $scope.data = response.data;

        });

});

21. What is AngularJS' "controller as" syntax?

"Controller as" is a way of aliasing controllers in AngularJS, making it easier to reference them in the view.

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<div ng-controller="MyController as vm">

    {{ vm.property }}

</div>

22. Explain the concept of $scope inheritance in AngularJS.

In AngularJS, child scopes inherit properties from their parent scopes. This allows data to be shared between parent and child scopes.

23. What is ng-include, and how is it used?

ng-include is a directive used for including HTML templates in other templates.

<div ng-include="'template.html'"></div>

24. What is the purpose of the $timeout service in AngularJS?

$timeout is used to delay the execution of a function by a specified amount of time.

25. Explain the concept of $rootScope.

$rootScope is the top-level scope in an AngularJS application. It is accessible to all controllers and can be used for global data.

26. What is AngularJS' $routeProvider?

$routeProvider is part of the ngRoute module and is used for defining routes in an AngularJS application.

27. What is ng-show and ng-hide used for? Provide examples.

ng-show and ng-hide are directives used for showing or hiding elements based on a condition.

<div ng-show="isVisible">This is visible</div>

<div ng-hide="isHidden">This is hidden</div>

28. How can you handle form submissions in AngularJS?

You can use the ng-submit directive to handle form submissions in AngularJS.

<form ng-submit="submitForm()">

    <!-- Form fields here -->

    <button type="submit">Submit</button>

</form>

29. What is the purpose of ng-disabled? Provide an example.

ng-disabled is used to disable or enable form elements based on a condition.

<button ng-disabled="isDisabled">Submit</button>

30. What is the AngularJS expression and how is it different from JavaScript expressions?

AngularJS expressions are similar to JavaScript expressions but have some differences. They are used in templates to bind data to the view. For example, {{ expression }}.

31. What is ng-bind and ng-bind-html?

ng-bind is a directive used for data binding. It updates the text content of an HTML element.

ng-bind-html is similar but allows binding HTML content, rendering it as HTML.

32. Explain the concept of custom directives in AngularJS.

Custom directives allow you to create reusable components with custom behavior and templates. They are defined using the directive method.

app.directive('myDirective', function() {

    return {

        restrict: 'E',

        template: '<div>This is my custom directive</div>'

    };

});

33. What is the purpose of the $routeProvider in AngularJS routing?

The $routeProvider is used to define routes and their associated templates and controllers in an AngularJS application.

34. What is the purpose of ng-options in AngularJS? Provide an example.

ng-options is used to generate the options for a <select> element based on an array.

<select ng-model="selectedItem" ng-options="item for item in items"></select>

35. What is ng-transclude, and how is it used?

ng-transclude is a directive that allows you to include content from the parent directive's template into the child directive.

<div ng-transclude></div>

36. What is AngularJS' "controller as" syntax and why is it beneficial?

"Controller as" syntax allows you to alias controllers in your views, making it easier to reference them and reducing the risk of scope conflicts.

37. Explain the concept of a digest cycle in AngularJS.

A digest cycle is the process through which AngularJS synchronizes the data between the model and the view. It checks for changes in the model and updates the view accordingly.

38. What is AngularJS' ng-init directive?

ng-init is a directive used to initialize variables in the scope. While it can be used, it's generally recommended to initialize variables in the controller.

39. What is the purpose of $watch in AngularJS? Provide an example.

$watch is used to watch for changes in a variable and execute a function when the variable changes.

$scope.$watch('myVariable', function(newVal, oldVal) {

    // Do something when myVariable changes

});

40. What is the purpose of the AngularJS $httpBackend service?

$httpBackend is a mock HTTP backend used for testing AngularJS applications. It intercepts and handles HTTP requests made by the application during testing.

41. What is the purpose of the AngularJS ngMock module?

ngMock is a module in AngularJS that provides utilities for testing, including mocking services and simulating events.

42. Explain the concept of the ng-animate module in AngularJS.

ngAnimate is a module that provides support for animations and transitions in AngularJS applications. It allows you to create smooth animations when elements enter or leave the DOM.

43. What is the purpose of the AngularJS ngModelController?

ngModelController is a controller used for managing the state of <input> elements with the ng-model directive. It handles validation, formatting, and parsing of input data.

44. What is the purpose of the AngularJS ngTouch module?

ngTouch is a module that provides touch event support and gestures for mobile devices in AngularJS applications.

45. How do you handle errors in AngularJS $http requests?

You can use the .catch() method or provide an error callback in the promise returned by the $http service.

$http.get('/api/data')

    .then(function(response) {

        // Success logic

    })

    .catch(function(error) {

        // Error handling

    });

46. What is AngularJS' ng-cloak directive?

ng-cloak is a directive that prevents the display of uncompiled AngularJS expressions while the application is loading.

47. What is AngularJS' ng-bind-template directive? Provide an example.

ng-bind-template is a directive that allows you to bind multiple expressions to an element.

<div ng-bind-template="{{ firstName }} {{ lastName }}"></div>

48. How can you create a custom filter in AngularJS?

You can create a custom filter by defining a function and registering it using the filter method.

app.filter('customFilter', function() {

    return function(input) {

        // Filter logic here

    };

});

49. Explain AngularJS' ng-include directive.

ng-include is used to include external HTML templates in an AngularJS application. It dynamically loads and inserts the template into the DOM.

50.What is AngularJS' ng-animate module used for?

ng-animate is a module used for adding animations and transitions to elements in AngularJS applications. It provides classes and hooks for defining animations based on CSS transitions.