Ember.js Interview Questions

A list of top frequently asked Ember.js interview questions and answers are given below.

1) What is Ember.js?

The Ember.js is a Model-View-ViewModel (MVVM) pattern based, JavaScript web framework. It is an open source framework which is used to create scalable single-page web applications.

2) How popular is Ember.js web framework?

According to a research Ember.JS has a market share of about 14.69%. So, it is an excellent opportunity to move ahead in your career in Ember.JS Development.

3) What is the core concept of Ember.js?

Following are some concepts used in Ember.js:

• Store: This is a central repository and cache of all records available in an application. Controller and admin can access it.
• Models: It specifies a class which defines the data of properties and behavior.
• Records: It specifies an instance of a model which contains loaded information from a server.
• Adapter: It is responsible for translating requested records into the appropriate calls.
• Serializer: It is used to translate JSON data into a record object.
• Automatic Caching: It is used for caching.

4) Why is Ember.js so popular?

The best thing about Ember.js is that it develops applications which are fastest in the running in the browser.

5) Who was the author of Ember.js?

Ember.js was developed by Yehuda Katz and initially released on in December 2011.

6) What are the main advantages of using Ember.js?

• It is an open source framework. So, it gives developers unlimited access for customizing for desired output.
• Ember.js doesn't require server requests to perform its task.
• DOM is directly updated when a user comes in contact with the browser or press any button over there.

7) What do you know about Model in Ember.js?

A model is a beneficial useful approach in Ember.js. It is used to store persistent state in an Ember application. It is used to reduce the complexity of the task. Templates can merely be supported, and developers can always make sure of required data that is necessary display with the HTML page. This data is generally in the form of text, and there can be a limit on the same depending on some factors.

8) What are the features of Ember.js?

• It contains HTML and CSS at the core of the development model.
• It is used to develop reusable JavaScript web applications.
• It provides the instance initializers.
• It can be used to manage the URL.

9) What is a router in Ember.js?

A router is a core feature of Ember.js. It is used to translate the URL into the series of templates and also represent the state of an application. Every URL has a corresponding route object that controls what is visible to the user. It matches the current URL to other routes which are used for loading the data, displaying the templates and set up an application state.

10) What is the different type of route models in Ember.js?

• MDynamic Models - It provides the routes with dynamic segments. These segments are used to access the value from URL

• Multiple Models - It is used to define multiple models through RSVP.hash. For example:

11) What are the main components of Ember.js?

Following is a list of main components of Ember.js:

• Models
• The Router
• Controllers
• Views
• Components
• Templates
• Helpers

12) Explain the architectural structure of Ember.js applications?

The architectural structure of the Ember.js application is based on MVC (Model, View, Controller) pattern.

• Models: Models define the data that is used in an application.
• Controllers: Controllers are used to modifying the queries, edit the data and provide user interactions.
• Views: Views are used to display the data and capture the user actions to be repeated easily if needed in the future.

13) How can you define a new class in Ember.js?

In Ember.js, we can call the extend() method on Ember.Object to define a new ember class.

Example:

The above example defines a new App.Person class with a say() method.

We can also create a subclass from any existing class by calling its extend() method. See the following example if you want to create a subclass of Ember's built-in Ember.View class.

Example:

While defining a subclass, you can override methods but still access the implementation of your parent class by calling the special _super() method.

Example:

14) What is the difference between Ember.js and other traditional web applications?

Ember.js is preferred over the majority of other traditional web applications due to many reasons. In the application's logic living on the server, an ember.js application downloads everything it required to run in the initial page load. So, it facilitates users not to load a new page every time while using the app. That's why the UI of Ember.js responds quickly. The advantage of this architecture is that your web application uses the same REST API as your native app.

15) What are services in Ember.js?

In Ember.js, a service is a long-lived Ember object that can be available in different parts of your application. The following syntax is used to create the Ember.js service.

Syntax:

Following is a list of some examples of Ember.js services:

• Logging
• User/session authentication
• Geolocation
• Third-party API's
• Web Sockets
• Server sent events or notifications
• Server-backed API calls that may not fit ember-data etc.

Ember CLI service generator is used to generate the service. To get access to a service, inject it either in an initializer or use the following syntax:

Syntax:

By using this method, you can also access the properties and methods using services.

Use the following syntax to define a service.

Syntax:

16) What are the most crucial tasks performed by controllers in Ember.js?

The most crucial task performed by a controller in Ember.js is decorating the model, which is returned by the route. In Ember.js, it is handled by controllers. It is not always necessary that only a single controller performs this task, but there may be required multiple controllers depending on the task itself. Besides this, there are many actions that users perform, and listening to these actions is also the responsibility of the controllers in Ember.js.

17) Which of the Ember.js function is actually a Boolean Function?

Log Binding is an Ember.js function that is actually a Boolean function.

18) What is Ember-data in Ember.js?

In Ember.js, Ember-Data is a library used to retrieve records from a server, store them, and update them in the browser. At last, it also saves them back to the server.

19) What do you understand by ember route? How can you generate a route in Ember.js?

The Ember.Route class is used to define individual routes in Ember.js. An ember route is built with three parts:

• The first part is the entry in the Ember router (/app/router. js ), ) which maps between our route name and a specific URI.
• The second one is the route handler file, which is used to set up what should happen when that route is loaded.
• The third one is the route template, which is used to specify where we display the actual content for the page.

In Ember.js, when we want to make a new page that we can visit using a URL, we need to generate a "route" using Ember CLI. Hence the generator will print out:

• Installing route
• Create app/routes/about.hbs
• Create app/templates/about.hbs
• Updating router
• Add route about
• Installing route test

If you want to define a route, run the following command:

Syntax:

The above command will generate a file name route-name.js in app/routes/ folder, a template for the route at app/templates/route-name.hbs, and a unit test file at tests/unit/routes/route-name-test.js. It will also add the route to the router.

20) What is an adapter in Ember.js, and why is it used?

In Ember Data, an Adapter is used to determine how data is persisted to a backend data store. Things such as the backend host, URL format, and headers used to talk to a REST API can all be configured in an adapter. For example, the rest adapter is used to deal with JSON APIs, and LSAdapter deals with local storage.

21) What are the two different ways of defining and inserting a view in Ember.js?

There are two ways of defining and inserting a view in Ember.js:

The first way to define and insert a view

• Extend the Em.View class, and create an object in your JavaScript to define a view. You can declare your functions and variables inside that.
• Insert a view in your template. Now, follow the syntax given to write the handlebar script {{ #view App.ViewName}}

The second way to define and insert a view

• In this technique, you don't need to specify the name of the view object while inserting it into the template. But inside the object, another property called templateName should be initialized with the same value as the data template name attribute in the handlebar's script tag in your template.

22) What do Ember.js components specify?

The Ember.js components use the W3C web component specification and provide correct encapsulation UI widgets. It contains the three main specifications as templates, shadow DOM, and custom elements.

The components are declared within the data-template-name have a pathname instead of a plain string.

23) What do you know about Ember.js structure?

Ember.js follows Models, Views and Controller structure. It is abbreviated as MVC.

Model: Model is used to define the data which is present and is useful for the developer.

View: View is used to display the data and also capture the action of the users to use when needed.

Controller: Controller is used to modifying a query. It also modifies the data and offers user interactions in the most reliable manner.

24) What is the difference between Route and Router in Ember.js?

Route and Router both are different terms in Ember.js. A router is a medium which is used to connect the application with a browser's address. On the other side, Route is a location where the request of a user reaches first after it is made or translated by a Router. Route only is responsible for defining the data that is to be sent to the Template.

25) Which function in Ember.js is a Boolean function?

Log Binding function is a Boolean function in Ember.js.

26) Which function in Ember.js is used to test whether the value is an array or not?

The isArray function is used to check whether the value is an array or not. It returns true if the passed object is an array or Array-like. The Objects are considered to be Array-like if any of the following are true:

• The object is a native Array
• The object has an objectAt property
• The object is an Object and has a length property

27) What is the use of Router and {{outlet}} tag in ember.js?

A router is used to specify all the possible states of an app and map them to URLs while {{outlet}} tag is used to build a hierarchy of sections by providing a mean for a container template to include a child template.

28) What is the role of adapters in Ember.js?

An adapter is used to handle queries related to the task assigned to it. Different adapters can be assigned different tasks. It can also query the back as well as front end. The common adapters in Ember.js are Rest, JSON, LS Adapter and the later deals with local storage or when data that needs to be stored in low.

29) What is the use of a template in Ember.js?

In Ember.js, a template is used to create a layout for one or more page. When we change a template, the pages based on that template changes automatically.

30) What are the different Template components in Ember.js? Is there any similarity between them?

Various template components are potent in Ember.js and are used for specific purposes related to running the code in an error-free manner.

These template components are:

• View
• Outlet
• Render
• Partial
• Yield

They are similar in one aspect, and that is they can be called in all the programs with similar functions.

31) What are the different common functions of Ember.js packages?>

The different common functions of Ember.js package are:

• empty - It returns true if the value of the dependent property is null, an empty array, empty string, or empty function.
• bind - It provides an easy way to integrate third-party libraries into your Ember application asynchronously.
• isArray - It returns true if the passed object is an array or Array-like.
• compare - It compares two javascript values.
• typeOf - It returns a consistent type for the passed object.
• isEqual - It compares two objects, returning true if they are equal

32) Which steps are used to create an app in Ember.js?

You have to use the following steps to create an application in ember.js:

• First, install an ember-cli. Almost all applications are built with ember-cli.
• Create a new application by using ember new. It generates a new application.
• Use materialize-CSS for styling to give a material design.
• Create components by using ember g component.
• Check whether there is a router.js file. It defines all your routes.
• If you have a video route and you would like to display a set of YouTube videos on the page then create a simple video card component that iterated over and display on the video page.

33) Explain the directory structure in Ember.js.

In Ember.js, project structure is also called directory structure. It contains the following files and directories:

I-app: It contains folders and files for models, components, routes, templates, and styles.

I-bower_components/ bower.json: It is a dependency management tool which is used in Ember CLI to manage front-end plugins and component dependencies.

I-config: It contains the environment.js which controls configure settings for your app.

I-dist: It contains the created output files when we build our app for deployment.

I-node_nodules/package.json: Directory and files are from npm. Npm is the package manager for node.js.

Public: The public directory contains assets such as image and fonts.

Vendor: This directory specifies a location where front-end dependencies that are not managed by Bower go.

Tests/testem.js: Automated tests for our app go in the test folder, and testing is configured in testem.js.

Tmp: Ember CLI temporary files live here.

Ember-cli-build.js: This file describes how Ember CLI should build our app.

34) What do you know by observers in Ember.js?

Ember supports observing any property which also includes computed properties. Observers are something which contains the behavior that reacts to the changes made in other properties. Observers are used when we need to perform some behavior after binding has finished synchronizing. New ember developers often use observers. Observers are mostly used within the ember framework and for that; computed properties are the appropriate solution. An observer can be set on an object using the following syntax- "ember.observer" Observers in ember are synchronous. They fire as soon as they observe a change in the properties. So, because of this, it is easy to introduce bugs where properties are not yet synchronized.

35) How to define a view in Ember.js?

36) What is Ember inspector?

The Ember inspector is a tool which is used to debug the code of an Ember application. It provides a way to interact with Ember objects and view its properties.

Some Most Frequently Asked Ember.js MCQ

1) Which of the following command is used to create an Ember.js application?

1. create application.js
2. ember application
3. ember new application
4. None of the above

2) What is the use of Ember.js services?

1. Ember.js services are used for logging.
2. Ember.js services are used for user authentication or session authentication.
3. Ember.js services are used to provide geolocation.
4. All of the above

3) Which of the following command is used to start the development server in Ember.js?

1. ember serve
2. ember start
3. ember begin
4. ember go

4) Which of the following command is used to stop the development server in Ember.js?

1. ember stop
2. Ctrl-C
3. Ctrl-B
4. ember break

5) What does a controller do in Ember.js?

1. A controller can decorate the model returned by the route.
2. A controller can listen to actions performed by users.
3. A and B both are correct.
4. None of the above.

6) Which of the template components are used in Ember.js?

1. Partial template component
2. View template component
3. Render template component
4. All of the above.