AngularJS Coding Interview Questions

Even though newer frameworks like Angular, React, and Vue dominate the frontend world, AngularJS still appears frequently in coding interviews. Many enterprise applications continue to rely on it, and companies need developers who can maintain or migrate these systems.

If you’re wondering how to study for a coding interview, mastering AngularJS questions will definitely give you an edge. Interviewers aren’t just checking your syntax knowledge. They want to see if you understand the MVC architecture, two-way data binding, directives, services, dependency injection, and how to apply them in real-world scenarios.

This guide covers everything you need to know about AngularJS: the basics, controllers, directives, services, routing, forms, promises, testing, performance optimization, and advanced-level problems.

By the end, you’ll be equipped with detailed answers, code snippets, and interview-style problems that help you confidently solve AngularJS questions and demonstrate your ability to work with legacy frameworks effectively.

Why AngularJS Is Still a Popular Choice in Coding Interviews

AngularJS may not be the newest framework, but it continues to play a role in coding interview prep for one big reason: enterprise adoption. Many organizations built large-scale applications with AngularJS years ago, and these systems are still in production. Maintaining, optimizing, or even migrating them requires developers who understand the framework well.

The simplicity of AngularJS for building single-page applications (SPAs) also makes it valuable for interviewers to test. It shows whether you can manage templates, controllers, and data binding efficiently.

For many roles, AngularJS is used as a filter: can you maintain older apps while applying modern best practices?

You’ll encounter many AngularJS coding interview questions because they test your ability to balance theory with practice, handling scopes, understanding the digest cycle, and implementing services in scalable ways. This makes AngularJS knowledge highly relevant even in today’s interview landscape.

Categories of AngularJS Coding Interview Questions

If you’re wondering how to practice for coding interviews and AngularJS, you should understand that it is easier if you break it down into categories. Here’s the roadmap this guide will cover:

AngularJS basics and architecture
Modules and controllers
Directives and data binding
Services and dependency injection
Filters
Forms and validation
Routing and navigation
Promises and $http service
Digest cycle and scope hierarchy
Testing in AngularJS (unit + end-to-end)
Performance optimization
Advanced AngularJS interview problems

Each section highlights not just definitions, but also practical code examples and interview-style solutions. By practicing across these categories, you’ll build the right strategy to prepare for a coding interview.

Basic AngularJS Coding Interview Questions

Q1. What is AngularJS and how is it different from Angular?

Answer: AngularJS is a JavaScript-based framework released by Google in 2010. It introduced the Model-View-Controller (MVC) approach, two-way data binding, and dependency injection for SPAs.

AngularJS is based on JavaScript.
Angular (2+) is based on TypeScript.
AngularJS uses controllers and $scope, while Angular uses components.

Sample Code:

<div ng-app>

  <p>{{ 5 + 5 }}</p>

</div>

Q2. Explain the MVC architecture in AngularJS

Model: Manages application data.
View: Handles the display using HTML templates.
Controller: Connects Model and View, handling logic with $scope.

Sample Code:

<div ng-app="myApp" ng-controller="myCtrl">

  <h1>{{ message }}</h1>

</div>

<script>

var app = angular.module('myApp', []);

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

  $scope.message = "Hello MVC!";

});

</script>

Q3. What is two-way data binding?

Two-way binding means changes in the model update the view, and changes in the view update the model automatically.

Sample Code:

<div ng-app="myApp" ng-controller="myCtrl">

  <input ng-model="name">

  <p>Hello {{ name }}</p>

</div>

Typing in the input instantly updates the paragraph text.

Q4. What are scopes in AngularJS?

$scope is the object that binds the controller with the view.
Variables defined on $scope can be accessed in the HTML template.

Sample Code:

<div ng-controller="myCtrl">

  <p>{{ user }}</p>

</div>

<script>

app.controller("myCtrl", function($scope) {

  $scope.user = "Interview Candidate";

});

</script>

Q5. Example: Write a simple AngularJS “Hello World” app

<!DOCTYPE html>

<html>

<head>

  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.8.2/angular.min.js"></script>

</head>

<body ng-app="helloApp" ng-controller="helloCtrl">

  <h1>{{ greeting }}</h1>

  <script>

    var app = angular.module("helloApp", []);

    app.controller("helloCtrl", function($scope) {

      $scope.greeting = "Hello World from AngularJS!";

    });

  </script>

</body>

</html>

Sample Answer: This demonstrates setting up a module, a controller, and binding data with $scope.

Many AngularJS coding interview questions start with these basics before diving into directives, services, or optimization.

Modules and Controllers

Q1. What is a module in AngularJS?

A module is a container for controllers, services, filters, and directives.
Defined using angular.module.

Code Example:

var app = angular.module(“myApp”, []);

Q2. How do you define and use controllers?

A controller defines the logic for a view.
Inject $scope to bind data.

Code Example:

<div ng-app="myApp" ng-controller="mainCtrl">

  <p>{{ greeting }}</p>

</div>

<script>

var app = angular.module("myApp", []);

app.controller("mainCtrl", function($scope) {

  $scope.greeting = "Hello from Controller!";

});

</script>

Q3. Difference between `$scope` and `$root` Scope

$scope: Local to the controller where it is defined.
$rootScope: Global scope, accessible across controllers.

Example:

<div ng-controller="firstCtrl">{{ msg }}</div>

<div ng-controller="secondCtrl">{{ msg }}</div>

<script>

app.run(function($rootScope) {

  $rootScope.msg = "Shared message";

});

</script>

Q4. Example: Build a module with multiple controllers

<div ng-controller="ctrlOne">{{ name }}</div>

<div ng-controller="ctrlTwo">{{ job }}</div>

<script>

var app = angular.module("multiApp", []);

app.controller("ctrlOne", function($scope) {

  $scope.name = "Alice";

});

app.controller("ctrlTwo", function($scope) {

  $scope.job = "Engineer";

});

</script>

Sample Answer: This shows how a module can manage multiple controllers, each with its own $scope.

Directives and Data Binding

Directives are one of the most important features in AngularJS. They extend HTML by attaching custom behavior to elements. If you’re preparing for interviews, expect multiple AngularJS coding interview questions focused on directives and binding.

Q1. What are directives in AngularJS?

Directives are markers on a DOM element (like attributes or tags) that tell AngularJS’s HTML compiler to attach behavior or transform the element. Examples: ng-model, ng-repeat, ng-if.

Q2. Difference between built-in and custom directives

Built-in directives: Provided by AngularJS, such as ng-model, ng-show, ng-hide, ng-repeat.
Custom directives: Defined by developers to create reusable components.

Q3. Example: Use ng-model and ng-bind for two-way binding

<div ng-app="myApp" ng-controller="myCtrl">

  <input type="text" ng-model="name">

  <p ng-bind="name"></p>

</div>

<script>

var app = angular.module("myApp", []);

app.controller("myCtrl", function($scope) {

  $scope.name = "Candidate";

});

</script>

Typing in the input updates the paragraph instantly. This is AngularJS’s two-way data binding in action.

Q4. How do you create a custom directive?

app.directive(“customMessage”, function() {

  return {

    restrict: “E”,

    template: “<h3>This is a custom directive!</h3>”

  };

});

Usage:

<custom-message></custom-message>

Answer: Custom directives help you encapsulate HTML + behavior, making code more modular and reusable.

Many AngularJS coding interview questions test your ability to explain and implement directives since they are the foundation of AngularJS’s declarative programming model.

Services and Dependency Injection

Services in AngularJS are singleton objects that provide reusable functionality across the application.

Q1. What is a service in AngularJS?

A service is a reusable component that contains logic or data shared across controllers, directives, and filters.
Example: $http, $location, $timeout.

Q2. Explain AngularJS dependency injection

Dependency Injection (DI) is how AngularJS supplies services to components. Instead of creating dependencies manually, you declare them, and AngularJS injects them automatically.

Q3. Difference between factory, service, and provider

Factory: Returns an object with reusable methods.
Service: Uses a constructor function and returns an instance.
Provider: More configurable, used during app configuration.

Q4. Example: Create a custom service for user authentication

app.factory(“AuthService”, function() {

  var user = null;

  return {

    login: function(name) { user = name; },

    getUser: function() { return user; }

  };

});

app.controller(“AuthCtrl”, function($scope, AuthService) {

  AuthService.login(“Alice”);

  $scope.currentUser = AuthService.getUser();

});

Answer: Services promote code reusability and maintainability. They’re a common focus in AngularJS coding interview questions because they show how well you understand app structure.

Filters in AngularJS

Filters format or transform data before displaying it in the view.

Q1. What are filters in AngularJS?

Filters are functions applied to expressions in templates to format data. Example: currency, date, uppercase.

Q2. Example: Format a date with a filter

<p>{{ today | date:”fullDate” }}</p>

Q3. Create a custom filter

app.filter(“capitalize”, function() {

  return function(input) {

    return input.charAt(0).toUpperCase() + input.slice(1);

  };

});

Usage:

<p>{{ “angular” | capitalize }}</p>

Q4. Difference between filters in expressions vs directives

In expressions: {{ name | uppercase }}
In directives: <p ng-bind="name | uppercase"></p>

Answer: Filters are often tested in interviews to see if you can present clean, formatted data.

Forms and Validation

Forms are a critical part of AngularJS applications, and interviews often focus on form handling.

Q1. How do forms work in AngularJS?

AngularJS attaches a FormController to forms, tracking their state.
Attributes like ng-model, ng-required, and ng-minlength enable validation.

Q2. Example: Build a login form with validation

<form name="loginForm" ng-submit="submitForm()" novalidate>

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

  <span ng-show="loginForm.username.$error.required">Username required</span>

  <input type="password" name="password" ng-model="password" required>

  <span ng-show="loginForm.password.$error.required">Password required</span>

  <button type="submit" ng-disabled="loginForm.$invalid">Login</button>

</form>

Q3. Explain ng-model, ng-form, ng-required

ng-model: Binds input fields to scope.
ng-form: Groups controls together.
ng-required: Marks fields as mandatory.

Q4. Difference between pristine, dirty, touched, and valid states

Pristine: Field not modified.
Dirty: Field modified.
Touched: Field visited.
Valid/Invalid: Field passes or fails validation.

Answer: Form states allow fine-grained validation feedback, a common topic in AngularJS coding interview questions.

Routing and Navigation

Routing allows AngularJS apps to behave like SPAs with multiple views.

Q1. What is routing in AngularJS?

Routing loads different templates and controllers based on the URL, without refreshing the page.

Q2. Difference between ngRoute and UI-Router

ngRoute: Official AngularJS router, simpler but limited.
UI-Router: Third-party router, supports nested views and states.

Q3. Example: Implement routing with multiple views

app.config(function($routeProvider) {

  $routeProvider

    .when(“/home”, {

      templateUrl: “home.html”,

      controller: “HomeCtrl”

    })

    .when(“/about”, {

      templateUrl: “about.html”,

      controller: “AboutCtrl”

    })

    .otherwise({ redirectTo: “/home” });

});

Q4. How do you handle route guards?

Use resolve in route configuration to ensure data is loaded before navigating.
Alternatively, write authentication checks before route changes.

Answer: Routing questions test whether you can build SPAs with structured navigation.

Promises and `$http` Service

The $http service is AngularJS’s way of handling AJAX calls, and promises are central to managing asynchronous operations.

Q1. How does `$http` work in AngularJS?

$http returns a promise that resolves with a response or rejects with an error.

Q2. Example: Fetch data from an API

app.controller(“ApiCtrl”, function($scope, $http) {

  $http.get(“https://api.example.com/users”)

    .then(function(response) {

      $scope.users = response.data;

    }, function(error) {

      console.error(“Error fetching data”, error);

    });

});

Q3. Difference between promises and callbacks

Callbacks: Execute after completion, but can lead to “callback hell.”
Promises: Cleaner syntax, error handling, and chaining.

Q4. How do you chain promises in AngularJS?

$http.get(“/api/user”)

  .then(function(user) {

    return $http.get(“/api/orders/” + user.data.id);

  })

  .then(function(orders) {

    console.log(“Orders:”, orders.data);

  });

Answer: Promise chaining avoids nested callbacks and keeps code readable.

Many AngularJS coding interview questions include $http and promises because they test your ability to handle real-world data fetching and async logic.

Digest Cycle and Scope Hierarchy

The digest cycle is at the core of AngularJS’s data-binding mechanism. Many AngularJS coding interview questions test whether you understand how scope changes are detected and propagated.

Q1. What is the digest cycle in AngularJS?

The digest cycle is AngularJS’s internal process of checking watchers for changes and updating the DOM.
Every time a scope variable changes, AngularJS runs a digest cycle to ensure the view reflects the new data.

Example: Typing in an input bound with ng-model automatically triggers a digest cycle.

Q2. How does `$apply` work?

$apply is used when you update a model outside AngularJS’s context (e.g., inside a raw JavaScript event).
$apply tells AngularJS to run a digest cycle manually.

$scope.updateData = function() {

  $scope.$apply(function() {

    $scope.message = “Updated outside AngularJS!”;

  });

};

Q3. Example: Demonstrate scope inheritance with nested controllers

app.controller(“ParentCtrl”, function($scope) {

  $scope.title = “Parent Scope”;

});

app.controller(“ChildCtrl”, function($scope) {

  $scope.subtitle = “Child Scope”;

});

<div ng-controller="ParentCtrl">

  {{ title }}

  <div ng-controller="ChildCtrl">

    {{ title }} – {{ subtitle }}

  </div>

</div>

Answer: The child scope inherits the parent’s properties unless they are shadowed.

Q4. What are watchers in AngularJS and how do they affect performance?

A watcher tracks changes on a scope variable.
Too many watchers can slow down performance because the digest cycle checks them all.
Use one-time binding (::) to reduce watchers.

Interviewers ask about the digest cycle to check if you understand AngularJS’s performance model.

Testing in AngularJS

Testing is a critical skill in frontend interviews, and AngularJS provides strong testing support.

Q1. How do you test controllers in AngularJS with Jasmine/Karma?

Jasmine provides a test framework.
Karma runs the tests.

describe(“MainCtrl”, function() {

  beforeEach(module(“myApp”));

  var $controller;

  beforeEach(inject(function(_$controller_){

    $controller = _$controller_;

  }));

  it(“sets the title”, function() {

    var $scope = {};

    var controller = $controller(“MainCtrl”, { $scope: $scope });

    expect($scope.title).toEqual(“Hello AngularJS”);

  });

});

Q2. What is end-to-end testing with Protractor?

Protractor simulates a real browser environment.
It’s used for testing user interactions with AngularJS applications.

Q3. Example: Test a service with dependency injection

describe(“AuthService”, function() {

  beforeEach(module(“myApp”));

  var AuthService;

  beforeEach(inject(function(_AuthService_){

    AuthService = _AuthService_;

  }));

  it(“should login a user”, function() {

    AuthService.login(“Alice”);

    expect(AuthService.getUser()).toEqual(“Alice”);

  });

});

Many AngularJS coding interview questions focus on testing since it shows your ability to deliver maintainable apps.

Performance Optimization in AngularJS

Performance is a key interview theme, especially with legacy AngularJS apps.

Q1. What causes performance bottlenecks in AngularJS?

Too many watchers.
Nested scopes.
Large DOM manipulations.

Q2. How do you optimize watchers?

Use track by with ng-repeat.
Use one-time binding for static values:

<p>{{ ::username }}</p>

Q3. Example: Use one-time binding

<h2>{{ ::title }}</h2>

This prevents AngularJS from creating a watcher after the first binding.

Q4. Difference between `$digest` and `$apply`

$digest: Runs watchers for the current scope.
$apply: Triggers a full digest cycle, including all child scopes.

Q5. Best practices for large AngularJS applications

Minimize watchers.
Cache results when possible.
Break large controllers into smaller components.
Use AngularJS’s built-in directives instead of manipulating the DOM directly.

Performance-focused AngularJS coding interview questions help employers test if you can handle enterprise-scale applications.

Advanced AngularJS Coding Interview Questions

Advanced interviews often focus on AngularJS internals.

Q1. What are decorators in AngularJS?

Decorators allow you to modify or extend services before they’re used.

app.config(function($provide) {

  $provide.decorator(“$log”, function($delegate) {

    $delegate.debug = function(msg) {

      console.log(“DEBUG: ” + msg);

    };

    return $delegate;

  });

});

Q2. How does AngularJS handle `$q` promises?

$q is AngularJS’s promise library.
It simplifies async logic and integrates with the digest cycle.

var deferred = $q.defer();

deferred.promise.then(function(result) { console.log(result); });

deferred.resolve(“Success!”);

Q3. Explain AngularJS internals, like compile and link functions

Compile: Runs once, transforms the template.
Link: Attaches behavior to the scope.

Q4. Example: Build a reusable custom directive

app.directive(“tooltip”, function() {

  return {

    restrict: “A”,

    link: function(scope, element, attrs) {

      element.on(“mouseenter”, function() {

        alert(attrs.tooltip);

      });

    }

  };

});

These advanced AngularJS coding interview questions are often used to test deep framework knowledge for senior roles.

Practice Section: Mock AngularJS Coding Interview Questions

Here are 5 full-length practice problems with solutions:

Build a to-do app with add/remove functionality
- Use ng-repeat and ng-model.
Create a custom directive for a tooltip
- Add hover functionality to display text.
Fetch and display user data from an API using $http
- Show results with ng-repeat.
Build a form with nested validation
- Validate email + password with ng-required.
Implement routing with multiple views
- Use ngRoute for home and about views.

Practicing these scenarios mirrors real AngularJS coding interview questions you’ll face.

Tips for Solving AngularJS Coding Interview Questions

Write modular, reusable code.
Always explain trade-offs in your approach.
Be clear about performance optimizations (watchers, caching, one-time binding).
Demonstrate strong knowledge of $scope and the digest cycle.
Show comfort with directives, services, and $http.
Communicate your reasoning step by step to the interviewer.

Many candidates lose points not because of wrong answers, but because they don’t explain their thought process clearly.

Wrapping Up

Mastering AngularJS coding interview questions will give you confidence in both frontend and full-stack roles. Even though newer frameworks exist, AngularJS knowledge is still valuable for legacy projects and migration work.

Keep practicing algorithms, working on AngularJS mini-projects, and refining your understanding of scopes, directives, and performance.

Code in AngularJS daily, revisit fundamentals often, and practice interview-style problems to stay sharp.

AngularJS Coding Interview Questions​

Why AngularJS Is Still a Popular Choice in Coding Interviews

Categories of AngularJS Coding Interview Questions

Basic AngularJS Coding Interview Questions

Q1. What is AngularJS and how is it different from Angular?

Q2. Explain the MVC architecture in AngularJS

Q3. What is two-way data binding?

Q4. What are scopes in AngularJS?

Q5. Example: Write a simple AngularJS “Hello World” app

Modules and Controllers

Q1. What is a module in AngularJS?

Q2. How do you define and use controllers?

Q3. Difference between $scope and $root Scope

Q4. Example: Build a module with multiple controllers

Directives and Data Binding

Q1. What are directives in AngularJS?

Q2. Difference between built-in and custom directives

Q3. Example: Use ng-model and ng-bind for two-way binding

Q4. How do you create a custom directive?

Services and Dependency Injection

Q1. What is a service in AngularJS?

Q2. Explain AngularJS dependency injection

Q3. Difference between factory, service, and provider

Q4. Example: Create a custom service for user authentication

Filters in AngularJS

Q1. What are filters in AngularJS?

Q2. Example: Format a date with a filter

Q3. Create a custom filter

Q4. Difference between filters in expressions vs directives

Forms and Validation

Q1. How do forms work in AngularJS?

Q2. Example: Build a login form with validation

Q3. Explain ng-model, ng-form, ng-required

Q4. Difference between pristine, dirty, touched, and valid states

Routing and Navigation

Q1. What is routing in AngularJS?

Q2. Difference between ngRoute and UI-Router

Q3. Example: Implement routing with multiple views

Q4. How do you handle route guards?

Promises and $http Service

Q1. How does $http work in AngularJS?

Q2. Example: Fetch data from an API

Q3. Difference between promises and callbacks

Q4. How do you chain promises in AngularJS?

Digest Cycle and Scope Hierarchy

Q1. What is the digest cycle in AngularJS?

Q2. How does $apply work?

Q3. Example: Demonstrate scope inheritance with nested controllers

Q4. What are watchers in AngularJS and how do they affect performance?

Testing in AngularJS

Q1. How do you test controllers in AngularJS with Jasmine/Karma?

Q2. What is end-to-end testing with Protractor?

Q3. Example: Test a service with dependency injection

Performance Optimization in AngularJS

Q1. What causes performance bottlenecks in AngularJS?

Q2. How do you optimize watchers?

Q3. Example: Use one-time binding

Q4. Difference between $digest and $apply

Q5. Best practices for large AngularJS applications

Advanced AngularJS Coding Interview Questions

Q1. What are decorators in AngularJS?

Q2. How does AngularJS handle $q promises?

Q3. Explain AngularJS internals, like compile and link functions

Q4. Example: Build a reusable custom directive

Practice Section: Mock AngularJS Coding Interview Questions

Tips for Solving AngularJS Coding Interview Questions

Wrapping Up

Related Guides