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Every IONIC project comes with a SET of pre-installed colours. This is how those colours are programmed:

• Navigate to the project/src/theme/variables.scss folder in your Ionic project.
• There will be a variable named $colours here that will hold the names of the VARIOUS colours as well as their hexadecimal COLOUR codes.
• Color codes for DEFAULT colours can be changed, and new colour names and hexadecimal codes can be added.

Ionic supports both internal and external storage of data:

• Internal Storage (SQLite) - If your app requires a strong database or you already have data to inject into your Ionic app, there's a wonderful underlying SQLite database WITHIN that you can utilise to store your data just like any other storage engine.
• External Storage (MySql, IndexedDB, WebSql, PouchDB, MONGODB) - You can even use different storage systems like MySql, MongoDB and so on. They have REMOTE databases and you connect to them and retrieve and WRITE data to their databases.
• Session, Cookie - Cookies help in ensuring that the site works properly and EFFICIENTLY when you visit it. Session cookies are temporary cookies that expire once you close the website and are not saved after your visit; they are generally not regarded to be intrusive of your privacy.

Using the following command, we can SEE a LIST of all AVAILABLE templates that can be used when creating a new Ionic application: ionic start --list.

Yes, FIREBASE is compatible with Ionic. It is one of the most powerful and widely used database-as-a-service SOLUTIONS on the market TODAY. The Firebase SDK can also be used as a NODE module. It can be installed, imported, and used within your project.

Config.xml is a global configuration file for Ionic applications that CONTROL the build settings. Many parts of a Cordova application's behaviors are controlled by it. A basic config.xml file is created for you in the top-level DIRECTORY when you build the Ionic application. The W3C Package Web applications (WIDGET) specification is followed in this file. It enables developers to quickly set metadata for their applications. It includes details about the project, like the package name, version, author information, plugins, platform, and so on.

A SAMPLE Config.xml file:

ionic PREPARE <platform> moves all files from the www folder to the www folder on the target platform. This is likewise done by ionic build <platform>, but it ALSO produces the app's SOURCE CODE so that it can be executed on a simulator/emulator or a device.

The following are some of the most essential ionic components:

• Ion-Alert: An alert is a dialogue that provides the user with vital information to help them make a decision or allows them to select a specific action or set of actions. It is shown over the app's content. Before resuming contact with the app, the user can remove it explicitly.
• Ion-Buttons: Using buttons to interact with and navigate around an application is vital. Its purpose is to make it apparent what will happen when the user clicks on them. Text, icons, or a combination of the two can be found on the buttons. To make it look a certain way, it can be upgraded with a range of features such as COLOUR, form, and size.
• Ion-Content: The Ionic content element ACTS as a container for all of the additional elements we wish to add to the app. The content component provides a simple content area with a few handy methods for controlling the scrollable area. A single view in an Ionic application should only have one content component. Individual styling with CSS and the appropriate CSS custom properties can ALSO be used to alter it.
• Ion-List: Lists consist of numerous rows of objects such as text, buttons, toggles, icons, thumbnails, and more. The list element is used to display data such as menus and tabs, as well as to break up the monotony of plain text files. Swiping things, dragging to reorder items inside the list, and removing items are all supported interactions.
• Ion-Input: This component is used to collect and securely handle user input. It functions SIMILARLY to an HTML input element. It only supports text inputs like text, passwords, numbers, emails, and URLS. It should be enclosed in the ion-item element at all times.

The Ionic grid system is indeed a mobile-based flexbox system that can be used to create a custom layout. The Ionic grid is made up of three primary components: a grid, rows, and columns. The Ionic grid consists of a 12-column layout with several breakpoints depending on screen size.

The following key points are to be remembered while dealing with an Ionic Grid:

• Grids are used to hold rows and columns together. It occupies the ENTIRE width of its CONTAINER, however, the fixed attribute specifies the width per screen size.
• Only columns should be immediate children of rows, as rows are horizontal groups of columns. Columns are where we put our contents, and only columns should be immediate children of rows.
• Out of the default 12 columns per row, the size attributes specify the number of columns to use. As a result, size="4" can be appended to a column to fill up 1/3 of the grid.
• If no size value is specified for a column, it will be AUTOMATICALLY divided into equal widths.
• Individual columns have padding PROPERTIES, although the padding can be eliminated from the grid and columns by setting no-padding on the grid.

The <ion-app> ELEMENT serves as a container for the whole Ionic app. The Ionic project should only contain one <ion-app> element and several Ionic COMPONENTS LIKE headers, footers, MENUS, content, and so on. When shown, all of these components are wrapped inside the <ion-app> component.

For example:

We ALREADY know that Ionic applications USE web technologies like HTML, CSS, and JavaScript. Web Views, which are full-screen and high-powered web browsers, are used to render these web technologies.

Numerous built-in HTML5 APIs for hardware capabilities are available in the current web view, including a camera, Bluetooth, GPS, sensors, and speakers. It may also require access to platform-specific APIs on occasion. The hardware APIs can be accessed through a bridge LAYER in the Ionic framework, which is commonly done by employing native plugins that expose JavaScript APIs.

A full explanation of webview architecture may be seen in the graphic below.

In the above image, we can see how ionic applications DIFFER from native applications. There are two additional layers of Bridge and a Web-View in the case of ionic applications.

Ionic 4 is based on ANGULAR and leverages RouterModule, an Angular router module, for navigation. It gives the entire application a more consistent routing experience. The NavController service was used for navigation in prior versions of Ionic, and it is still available, although it will be deprecated shortly. As a result, in new Ionic applications built with Ionic 4, it will not be encouraged.

The ion-router-outlet COMPONENT is used in the CURRENT version of Ionic to control the animations that appear as the USER moves to or from a component inside the app. The ion-router-outlet is similar to the Angular router-outlet, but with the addition of an animation effect.

AngularJS is used to create Ionic v1 applications. Jasmine and the Karma test runner are two of the many test libraries and frameworks available with Angular. Unit tests for Ionic applications may be written using these frameworks. Ionic applications can be tested in four different ways: on a desktop WebKit browser, in an iOS or Android emulator, in a MOBILE browser on your phone, or as a native application on your phone. Ionic-CLI ALSO has a live reload capability that allows you to test your application in the browser. The ionic serve COMMAND, for example, can be used to load the application in any browser. To debug and investigate Ionic applications, we can UTILISE Chrome Developer Tools or Mozilla Firefox with Firebug.

The concept underlying lazy loading is that we only load the HTML, CSS, and JavaScript that our application requires to render its first route, and then load other COMPONENTS as needed. The good news is that a new Ionic Angular 4.0 app comes pre-configured with lazy loading.

Lazy loading is a method in which we load THINGS only when we need them. The fundamental idea behind such a notion is that when the application is opened, we don't need to load every page in it. The @IonicPage decorator was advised in PREVIOUS versions of the Ionic framework to sleepy load your pages, but in the latest version of Ionic (Ionic 4), we lazy load our Angular components using Angular routing. Each Ionic component is a web component, and these components will only be loaded lazily when they are used in the Ionic application.

When you use the tabs starter template to create a new Ionic app, this is the first route that is created for you. The Angular router will dynamically load this file when the user navigates to the route if you specify a loadChildren string instead of passing a page class to component. This JavaScript is also separated from the rest of the app and placed in its own bundle.

The routes in the tabs routing module are set up as follows:

Each tab in this configuration loads its children SLOWLY, thus all of tab2's files aren't loaded until the user clicks on the tab2 page.

We can avoid the browser having to download, process, and compile our entire programme before the user interacts with the first page by dividing it up into smaller lazily loaded pieces. If our app was large, this would significantly increase the program's first load time.

Optimizing Lazy Loading:

You can provide a pre-loading strategy when importing the Router module into the main app module. There are two that come with Angular out of the box:

• NoPreloading: No preloading of lazily loaded modules is done. If no strategy is specified, this is the default behaviour.
• PreloadAllModules: When the network becomes idle, this technique will preload all of the REMAINING modules once your app loads the initial module. This option is automatically established for you in the Ionic beginning templates.

The structure of an Ionic 4 application is identical to that of an Angular application. The root directory will contain the e2e, node modules, and src folders, as well as INDIVIDUAL files such as angular.json, ionic.config.json, package-lock.json, package.json, tsconfig.json, and tslint.json. The e2e/ folder CONTAINS files for running end to end integration tests, while node modules contain all dependencies. The majority of the application code you'll be BUILDING is in the src/app/ subdirectory. App.module.ts, app.component.ts, app.component.html, app.component.spec.ts, and app-routing.module.ts are the main files in the application folder. Any developed services, components, or pages can be saved in their own directories. Images and other static content can be stored in the assets/ subdirectory.

Angular.json contains all of the angular settings, such as the PROJECT NAME, application folder root path, source root, paths for index file, main.ts, polyfills, assets folder path, css stylesheet paths, script paths, build settings, and so on. During development, ionic.config.json can be used to set proxy settings for APIs to avoid CORS problems. package.json provides a list of dependencies as well as the commands serve, build, test, and e2e.

The RxJS LIBRARY EXPORTS a class called Observable. The RxJS library provides observables, which aren't specific to Ionic or Angular and are given by the RxJS library. Promises are comparable to observables, but observables can do a lot more. Rather than resolving a single value, it can deal with several values at once. You may even subscribe to an observable in order to change the DATA it contains. Observables are "lazy" in the sense that they will not be executed unless and until they are subscribed to. Observables can be modified and a new one RETURNED using a variety of procedures. Even better, you can make your own observable. With the help of a subject, the observable patterns are INTEGRATED into one, which is preferable for straightforward implementation.

Services are vital in the Ionic framework since they offer information to our application and help us with various tasks. Some of the services implemented in the ionic framework include ConnectivityMonitor, SimpleAlert, DATA, GoogleMaps, and others. When building service, there are a few ideas to keep in mind. The most CRUCIAL THING is to import a service, add a provider to it, and inject it. The services must be imported into the classes that will utilise them. When injected into a constructor, it creates a new member variable that can be accessed from anywhere in the class. There are two WAYS to add a provider to a service; It can either be introduced to a single component or added to the entire application when bootstrapping the root component.

The official Ionic CLI, or Command-Line-Interface, is a VITAL instrument for Ionic APPLICATION development. 

• It combines a VARIETY of tools into a single user interface.
• Start, build, serve, and run are just a few of the essential commands for Ionic development. It also has commands such as emulate and info, that can be useful under CERTAIN circumstances.
• It's also in charge of cloud builds and deployment, as well as managing your Ionic Pro account.

To use Ionic CLI to create a new ionic project, type:

ionic start <project name> <template>, for example, new task blank. This will start a new project with a blank canvas. Instead of using blank as a beginning template, you can use tabs, side menus, and other OPTIONS.

The following points illustrate the differences between Ionic and PHONEGAP:

• Ionic is an open-source front-end framework for creating AngularJS-based cross-platform mobile apps. It enables the DEVELOPER to create a hybrid application using HTML, CSS, JavaScript, and SaaS. On the other hand, Adobe Systems created the PhoneGap framework. Anyone with a basic understanding of CSS, HTML, and JScript can use it to create mobile applications. PhoneGap is a fork of Apache Cordova that adds NEW functionalities to the existing Cordova framework.
• PhoneGap does not have a lot of community support. To use all functions, you'll need to purchase a licence. Ionic has received a lot of POSITIVE feedback from the community. All of the apps are completely free to use.
• Ionic IMPROVES the look and feel of mobile applications. Phonegap is a web-based user interface that does not provide a better look and feel for mobile apps.

• Native applications: Applications for specific devices, such as smartphones and tablets, are known as native applications. It can be downloaded via an application store (such as Google Play or APPLE's application Store) and installed straight on the device. They are available at all times on the smartphone and can be accessed via icons on the home screen. These applications can work offline and utilise the device's notification system. Camera, Collage-Maker, Google Maps, Facebook, and other well-known native applications are just a few examples.
• Mobile web applications: These are internet-enabled applications with features tailored to mobile devices. Web browsers on mobile devices are used to access mobile web applications. They do not require DOWNLOADING or installation on the device.
• Hybrid applications: These are the ones that incorporate features from both native and online applications. It can be installed on a device in the same way that any other application can. They are written with web technologies such as HTML, CSS, and JavaScript, and are similar to native applications. They're popular because they enable developers to write only ONE piece of CODE for a mobile application and PUBLISH it across various platforms.

The Advantages of using an Ionic framework are:

• Simple to learn: Learning and producing applications utilising the Ionic framework is simple if the developer has a basic understanding of CSS, HTML, or JavaScript frameworks. It also permits DEVELOPMENT firms to convert to Ionic if their demands and requirements necessitate hybrid application development.
• Documentation is simple: Ionic has excellent and well-organized documentation. The official documentation included the majority of what developers needed to know.
• Cross-platform: The ionic application may run on a VARIETY of platforms, including native iOS, Android, desktop, and the web, all from a single codebase. These applications are written once and run anywhere.
• Ionic's user interface: It includes themes and components, and is highly customisable. The ionic platform enables its components to adjust to the platform on which they are running.
• Built using AngularJS: The Ionic framework makes use of AngularJS, which gives developers a lot of options. AngularJS is the most popular framework among designers worldwide. Ionic can give a solid structure using AngularJS, making the code more comprehensible.

The DISADVANTAGES of using an Ionic framework are:

• Performance: When COMPARED to native mobile applications, the Ionic application performs poorly. However, most average users will not notice the performance difference.
• Security: An application built using the Ionic framework may not offer the same level of security as a native app. The Ionic framework, for example, is not suggested for designing a financial app, such as a bank app.
• Limited native functionality: The Ionic framework may or may not support some native functionalities. In this scenario, you'll have to create your own plugin to perform that function. However, there are numerous plugins that cover the majority of the native features.
• Not suitable for graphic-intensive applications: The Ionic framework is not suitable for applications or games that involve complex graphics.
• Expertise is required: JavaScript can be difficult to learn. As a result, someone who will not only "handle" JS but also has a thorough understanding of advanced libraries and technologies such as Angular, Cordova, Ionic, and others is required.
• The risk of being an early adopter: Ionic technology is still in evolution. Its support and standards are constantly changing, and its libraries can be fully redesigned at any point.

Ionic Framework V4 focuses heavily on speed, compatibility, and general extensibility. The following are the new features in Ionic 4.

• Web Components: One of the most significant changes in Ionic V4 is that each component is now a web component. A group of web platform APIs is known as web components. It enables developers to construct customised and reusable HTML tags for usage in web pages and web applications. Custom elements, HTML imports, HTML Templates, and Shadow DOM are the four key requirements.
• Capacitor: It's a cross-platform API with a code execution layer that makes calling Native SDKs from web applications simple. It also creates any custom Native plugins your application may require. It also allows the DEVELOPER to create a single application and distribute it across application marketplaces and MOBILE websites.
• Stencil: The ionic team has produced a new web component compiler to create standards that are compatible with web servers. It also makes use of extra APIs that are best SUITED for PWAs, such as TYPESCRIPT, Virtual DOM, JSX, and async.
• Ion-Backdrop: They're full-screen components that overlay other components. They are used to dismiss the other component and are placed on top of the other component.
• Ion-Picker: On the top of the application content and at the bottom of the viewport, it shows a row of buttons and columns.
• Ion-Ripple Effect: The ripple effect is a component that adds the ink ripple interaction effect from Material Design. It's DESIGNED to be fast, non-intrusive, and easy to use without adding any more DOM to the elements. For CSS-Only implementation, it works without degrading JavaScript.
• Ion-Searchbar: This component consists of a text field that is used to search a collection. In version 4, the Ionic team has implemented nine alternative search bar designs.
• Color changes: The Ionic framework's default colour has been modified, and several new default colours have been introduced.
• CSS Variables: These are the Ionic framework's highlighting features. Without utilising the build tools, it will change the entire appearance and feel of the programme by making minor changes to a few variables.
• Lazy Loading: It is a design approach used in the Ionic framework to delay component initialization until it is required. By breaking the application into numerous bundles and loading it on demand, it improves performance and reduces application load time.

The following are the features of the Ionic framework:

• Cross-platform: The Ionic framework allows the application to be deployed across many platforms, including Android, native iOS, desktop, and the web as a dynamic web app, all from a single codebase. As a result, Ionic applications can be written once and run anywhere.
• Based on Web Standards: The ionic framework is designed utilising contemporary web APIs and is based on trustworthy, standard web technologies such as HTML, CSS, and JavaScript (like Custom Elements and SHADOW DOM). As a result, Ionic components have a consistent API, allowing Ionic applications to function on different platforms.
• Helps in Creating Beautiful Design: We can create a clean, straightforward, and useful application USING the Ionic framework. Pre-designed components, typography, engaging paradigms, and a beautiful basic theme are all included in the Ionic application.
• Cordova Plugin: It provides the API for calling native device functions from JavaScript code.
• License: Ionic Framework is a free and open-source project published under the MIT licence. It means we can use it for free in both personal and business endeavours.
• Ionic CLI: The Ionic CLI, or COMMAND Line Interface, is a resource that enables Ionic developers with a number of useful commands. It's a command that allows you to start, develop, execute, and emulate Ionic applications.
• Framework Compatibility: Ionic's previous editions were intimately linked to Angular. However, the most recent version of Ionic, v4, has been re-engineered to SERVE as a standalone web component library with support for the most recent JavaScript frameworks. It's also compatible with most front-end frameworks.
• JavaScript Components: It adds JavaScript functionality to CSS components to COVER all mobile aspects that can't be done with HTML and CSS alone.
• Angular: Angular is responsible for the greatness of the Ionic framework. While the main components can be used independently, the angular package simplifies integration with the Angular ecosystem. The angular package includes all of the features that Angular developers would anticipate, as well as integration with the core libraries of Angular.