Ionic interview questions OR hybrid mobile app interview questions -
1. What is Ionic Framework?
The IONIC framework is an HTML5 platform that allows web developers (UI developer) to build hybrid mobile applications. Hybrid apps are those apps that have all access of native perform functionality and or you can say it is small websites running in browser shell in the application. It is a powerful HTML5 SDK that helps peoples to build mobile apps using HTML, CSS, and JavaScript. Ionic framework mainly focus on the look and feel of the app and its UI interaction. Ionic very fits well with the front end part of your app. It is free to use under MIT license so that it can be used for personal or commercial applications/projects.
2. What are the advantages and disadvantages of building hybrid/mobile applications using the Ionic framework?
The most obvious advantages are:
1. The ionic framework builds hybrid applications using web technologies. It means web developers can very easily build mobile applications too. Also, because it uses JavaScript / angular, almost the same codebase can be used to build both iOS and Android applications.
2. Development cost is less compared to native iOS and Android applications.
3. The ionic framework is excellent for quick application ideas prototyping.
Some of the disadvantages are:
4. It is not suited for high-end graphics dependent applications or games.
5. Performances are not as good as native applications, namely animations, scrolling, and network operations.
6. As mentioned, JavaScript animations are not as performant as native animations. However, there are JavaScript / angular libraries, like chartjs, which provide decent graph UI performance on the devices.
3. Explain what is the difference between "ionic build and ionic prepare” commands?
ionic prepare
ionic build
4. Explain some of Useful Ionic Commands.
Please check commands and its description -
1. start- This command is used to create a new project.
2. serve- This command is used to start a local dev server for app dev/testing.
3. generate- This command is used to generate pipes, components, pages, directives, providers, and tabs.
4. docs - This command is used to open the Ionic documentation website.
5. build - This command is used to build web assets and prepare your app for any platform targets.
6. link- This command is used to connect your local app to Ionic.
7. info - This command is used to print system/environment info.
8. login- This command is used to log in with your Ionic ID.
9. signup - This command is used to create an Ionic account.
10. upload- This command is used to upload a new snapshot of your app.
11. telemetry- This command is used to opt in and out of telemetry.
12. config set- This command is used to set config values.
13. config get- This command is used to print config values.
14. cordova compile- This command is used to compile native platform code.
15. cordova build- This command is used to build an Ionic project for a given platform.
16. cordova emulate- This command is used to emulate an Ionic project on a simulator or emulator.
17. cordova plugin - This command is used to manage Cordova plugins.
18. cordova platform- This command is used to manage Cordova platform targets.
19. cordova resources - This command is used to automatically create icon and splash screen resources.
20. cordova prepare - This command is used to copies assets to Cordova platforms, preparing them for native builds.
21. package download- This command is used to download your packaged app.
22. package build- This command is used to start a package build.
23. package list - This command is used to list your cloud builds.
24. cordova run - This command is used to run an Ionic project on a connected device.
25. package info - This command is used to get info about a build.
5. How to use service/providers in Ionic?
Services play a very important role in Ionic as you already know they provide information to our application and perform various tasks for us. SimpleAlert, data, ConnectivityMonitor, GoogleMaps, etc. are some of the services which are built in ionic framework. There are a few points which are to be kept in mind while creating a service. Adding a provider to it, Importing a service and injecting it is the most important thing. The services should be imported into the classes where they are going to be used. When it is injected inside a constructor, a new member variable is created which can be accessed from anywhere within the class. A provider can be added in a service by two ways - Either it can be added to an individual component, or it can be added globally to the application when bootstrapping the root component.
6. Explain the difference between PhoneGap, Cordova, and Ionic?
PhoneGap is a library that exposes native mobile phone functionalities as JavaScript API. When Adobe purchased PhoneGap, its open source core was donated to the Apache Software Foundation under the name Cordova. In the beginning, there was almost no difference between Cordova and PhoneGap. Although, over the years of development, Adobe started adding a proprietary set of the services to PhoneGap. Today, it is safe to say PhoneGap is Cordova plus extra Adobe services. Ionic uses Cordova, not PhoneGap for its core tools. Beside native mobile phone functionalities, Ionic gives structure and code scalability to JavaScript applications by using AngularJS. It also provides a set of Angular directives and components to speed up application development.
7. How to use observables in an Ionic framework?
Observables are something that is not specific to Ionic or Angular. It is provided by the RxJS library. Observables are almost similar to the promises but can do a lot more. It can deal with multiple values at a time rather than just resolving one value. You can even subscribe to an observable to manipulate the data which is associated with it. Observables are considered to be “lazy”, i.e. they won’t get executed until and unless they are subscribed to. Various operations can be applied to the observables for modifying it and returning a new one. You can even create your own observable. The observable patterns are combined into one with the help of the subject which is preferred for simple implementations.
8. What is Ionic Market?
The ionic market provides ready starter, plugins, themes etc. for the developer to download them and use for their own projects.
9. How do you persist data between application launches using the Ionic framework?
As Ionic behind the scene builds HTML5 based applications, you can use localStorage and sessionStorage API to persist data on the mobile phone. However, since localStorage can only store strings, objects need to be stringified before saving. Also, it is important to mention localStorage has size limit around 5MB.
10. How do you pass data from one view to another in Ionic applications?
You can use the NavController and NavParams to send data to pages that you push
11. Give some examples of hybrid mobile app frameworks?
re are several frameworks are available for hybrid mobile app development.
• Mobile Angular UI
• Intel XDX
• PhoneGap
• Ionic
• Appcelerator Titanium
• Kendo UI
12. How can you render a 5000 item list in Ionic, without affecting scroll performance?
Ionic provides a collection-repeat directive that renders only visible items in the DOM. So even if the list is huge, like 5000 in our example, only items visible in a viewport are rendered. Thus, scroll performance is not affected.
13. How To Generating New Pipes, Tabs, Components and Pages using Ionic 3 and Angular 4?
Ionic 3 CLI Commands For Angular 4 Projects
1. Pipes,
2. Providers and
3. Directives,
4. Components,
5. Tabs
Syntax –
- ionic generate [pipes] [pipes-name]
- ionic generate [providers] [providers-name]
- ionic generate [directives] [directives-name]
- ionic generate [components] [components-name]
- ionic generate [tabs] [tabs-name]
Example –
- ionic generate pipe
- ionic generate provider
- ionic generate directive
- ionic generate component
- ionic generate tabs
- ionic generate page
- ionic generate component demoApp
- ionic generate page Login
- ionic generate page register --no-module
- ionic generate page users --constants
- ionic generate pipe MyCustomPipe
14. What is the advantage of caching the views in Ionic apps? Provide examples.
Ionic by default caches up to ten views, which improves performance and also maintains different states in the views at the same time. For example - The cache can maintain scroll position in the views or active state of buttons.
15. What is the difference between native mobile app design and responsive web design? Do we really need both? Explain.
Mobile apps can be developed natively or as hybrid apps, while mobile-friendly websites can be developed as adaptive or responsive. The basic design process behind all of them is more or less the same. The only thing we need to consider when designing for mobile is that we have a specific set of rules we need to follow. Apple has its own, and so does Google.
When you’re designing for iOS or Android, the underlying process is the same. First, we do research that will outline best practices and show us what we can do on a certain platform and what not. Basically, research helps us we learn restrictions and take advantage of possibilities a given field.
Designers are likely to work on both native app and responsive web designs. Native apps are important because we want the user to have them on their dashboard, and this way we want to help users in their everyday activities. Some native apps can work offline while others can’t.
Responsive web design is important for SEO and Google indexing. So, if we want to have your project well-ranked on Google, you definitely go for a mobile-friendly responsive design.
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