js angular 2 Key Concepts and Improvements Explained

Angular 2 is a significant improvement over its predecessor, Angular JS. It's a complete rewrite, not just an update.

One of the key features of Angular 2 is its use of TypeScript, which provides better support for large applications and is more maintainable.

Angular 2 also introduced a new dependency injection system that makes it easier to manage dependencies between components. This makes it simpler to test and maintain code.

Components are the building blocks of Angular 2 applications, and they're a significant improvement over the directives used in Angular JS. Components are reusable and encapsulated, making it easier to build complex applications.

Related reading: Next Js Components

Angular 2 follows a component-based architecture, breaking down applications into reusable components.

This architecture makes applications easier to maintain and scale, as components can be reused throughout the application.

Angular 2's component-based architecture is built around the idea of breaking down applications into smaller, manageable pieces.

Here are the key components of Angular 2's architecture:

Angular's component-based architecture is a game-changer. It breaks down applications into reusable components, making them easier to maintain and scale.

These components are the building blocks of your application, and they can be reused across different parts of your project. Angular 2 uses TypeScript, a superset of JavaScript, which provides static typing and other features that improve code quality and developer experience.

Angular 2's component-based architecture is a significant improvement over AngularJS 1. With Angular 2, you can write complex directives using the @Directive decorator, giving you fine control over how the DOM is modified.

Here are the key components of Angular 2's architecture:

This architecture makes it easier to test and reuse code, and it's well-suited for developing mobile applications. With Angular 2, you can produce code that's optimized for performance and can run on a variety of devices.

The App Component is the entry point of your Angular application. It's the topmost component that bootstraps the application.

Angular 2 follows a component-based architecture, breaking down applications into reusable components, which is why the App Component is a crucial part of this architecture. It's essentially the container that holds all the other components together.

The App Component is similar to a View Model in the MVVM pattern, it controls a piece of UI by providing it with data and logic. This makes it a critical component in the overall architecture of your application.

Components are isolated and encapsulated units of UI, and the App Component is no exception. It contains its own view, view model, styles, and metadata, making it a self-contained unit.

Event bindings are one way to do one-way data binding from a view/template to a component, and the App Component can utilize this feature.

Additional reading: Angular Ui Bootstrap

Directives and Pipes are two powerful tools in Angular 2 that can greatly enhance your application's functionality. Directives can modify the behavior and appearance of HTML elements, creating custom tags and attributes for consistent use across the application.

Directives can also enhance the user interface by applying directives where needed. This can be particularly useful for creating reusable UI components.

Directives can be used to create custom HTML tags and attributes for consistent use across the application. Here are some key benefits of using directives:

Pipes, on the other hand, are used to transform data before displaying it to users. They can be used for filtering, formatting, and sorting data, making it easier to customize data presentation.

Directives are a powerful tool in Angular that let you modify the behavior and appearance of HTML elements. They can also create custom HTML tags and attributes for consistent use across your application.

You can use directives to enhance the user interface by applying them where needed. For instance, you can use structural directives like *ngFor and *ngIf to alter the structure (DOM) of your application.

Here are some key features of directives:

Structural directives like *ngFor and *ngIf are particularly useful, as they can alter the structure of the DOM. The asterisk is prepended to highlight the fact that a specific directive is going to alter the structure of your view.

Pipes are a powerful tool in Angular 2, allowing you to transform data before displaying it to users. They can be used for filtering, formatting, and sorting data.

You can create custom pipes by using the @Pipe decorator and implementing the PipeTransform interface. This gives you the flexibility to customize data presentation efficiently.

One of the most useful pipes in Angular 2 is the async pipe, which lets you subscribe to a Promise or an observable and returns the last value emitted.

To use pipes within your component, you need to declare them within the @Component decorator's pipes property. This ensures that your custom pipes are recognized and can be used throughout your application.

Here are some key benefits of using pipes in Angular 2:

Angular Concepts are built around the idea of reusable components, which makes them easier to maintain and scale. This is a key feature of Angular 2, where applications are built using reusable components.

Components are similar to View Models in the MVVM pattern, controlling a piece of UI by providing it with data and logic. They consist of a view (or template), metadata, and optionally styles, making them an isolated and encapsulated unit of UI.

You can pass data into a child component using @Input decorated properties, and from a child component to a parent component using @Output decorated events. This lets you pass a person to the PersonComponent from a parent component and subscribe to the changed event.

Here are some of the key features of Angular 2:

AngularJS 1 required you to create a controller, which was the fundamental "brain" of your application.

Controllers became very complex and had to deal with parent and child scopes, making understanding and debugging the application for the next developer a lot harder.

A typical AngularJS 1 controller looked like the one shown in Listing 1, but it was not the best approach.

AngularJS 2 replaces "thinking in controllers" with "thinking in components", which are the central artifact in AngularJS 2.

Components are similar to View Models in the MVVM pattern, controlling a piece of UI by providing it with data and logic.

Components can nest other components and give your "tag" its own CSS area, keeping your CSS separate from the page's CSS.

Here are the key differences between components and controllers:

Components are a more organized and efficient way to build applications, making them easier to maintain and scale.

AngularJS 2 requires you to think differently, with key differences compared to AngularJS 1.

The good news is that many concepts port over from AngularJS 1, making it easier for developers to adapt. As an AngularJS 1 developer, you'll clearly see the improvements where you see the differences.

Thinking in AngularJS 2 involves understanding the new syntax and features, which can be learned more easily than the complex directives in AngularJS 1.

Writing your own structural directives in AngularJS 2 is made possible with the @Directive decorator, giving you fine control over DOM modification.

This level of control is welcome, especially since modifying the DOM is one of the most expensive things your application does.

Components are the central artifact in AngularJS 2, replacing the need to "think in controllers" like in AngularJS 1.

A component can nest other components and even give your "tag" its own CSS area, preventing CSS conflicts with the page's CSS.

See what others are reading: Css 2 Columns

When choosing a language for AngularJS 2, you have several options. JavaScript is evolving and needs to scale to complex applications, so you need to pick a language that can keep up.

ES5 is a straightforward choice, but it's not strongly typed and doesn't offer code structure advantages. It's only JavaScript and doesn't need compilation.

ES6 is a superset of ES5, offering better code structure building blocks, but it's not strongly typed and still requires a compilation step. Browsers are taking a long time to support ES6 natively, which is a drawback.

TypeScript is a superset of ES6, making it a strong contender. It's strongly typed, giving you much better code structure building blocks, and it requires a compilation step. You can rename your .js file to .ts and pretend it's JavaScript, but it's actually a superset of JavaScript.

Dart seems to offer the worst of all worlds, requiring compilation and not being JavaScript. It gives you better code structure alternatives, but using it feels like using an entirely different language that doesn't mentally translate into JavaScript.

Here are the language choices in a nutshell:

TypeScript stands out as the clear winner, offering a balance of strong typing, better code structure, and compatibility with JavaScript. The AngularJS 2 team is also using it, which is a testament to its effectiveness.

AngularJS 1 had a steep learning curve due to its complex service system, which included Services, Providers, Factories, and more. This made it easy to get lost in the nuances of each.

The service system in AngularJS 1 was a major pain point, with many developers struggling to understand the intricacies of providers versus services versus factories. This led to a lot of confusion and frustration.

In contrast, AngularJS 2 introduced a class-based system, which simplified the development process. This was a major improvement, especially for developers familiar with languages like C# or Java.

The class-based system in AngularJS 2 eliminated the need to memorize complex service concepts. Instead, developers could focus on writing clean, maintainable code.

However, the class-based system also introduced a new problem: the magic string problem. This occurred when developers used strings to reference services, which could lead to typos and broken code.

In this review section, we'll recap the key takeaways from our Angular 2 journey so far.

We define how we want to compile TypeScript in our tsconfig.json file, which is crucial for setting up our project.

Our application is compiled and served by webpack-dev-server, making it easy to test and iterate on our code.

CIDER is a powerful tool for building out our components, such as AppComponent and HomeComponent.

To create an injectable service, we use the @Injectable() metadata, which allows us to share data between components.

The Angular 2 binding syntax is a bit different from what we're used to, but with practice, it becomes second nature.

Here's a quick summary of what we've covered so far:

AngularJS 2 requires a different way of thinking, but many concepts from AngularJS 1 still apply. As a developer, I've found that the new syntax and features in AngularJS 2 make it easier to learn and work with.

One key improvement in AngularJS 2 is the use of TypeScript, a superset of JavaScript that provides static typing and other features that improve code quality and developer experience. This makes it easier to catch errors and write more maintainable code.

AngularJS 2 also introduces a component-based architecture, which makes it easier to build and maintain applications. This is achieved through reusable components, which can be easily scaled and updated.

The new routing system in AngularJS 2 makes it easy to navigate between different views in your application. This is a significant improvement over the routing system in AngularJS 1, which has undergone evolution and improvements.

Error messages in AngularJS 2 are also a major improvement. Unlike in AngularJS 1, where error messages were often poorly worded and generic, AngularJS 2 provides much cleaner and more intuitive error messages.

Here are some of the key features that have improved in AngularJS 2:

AngularJS 2 also retains some of the concepts from AngularJS 1, such as modules, filters, and HTTP interactions. However, the syntax and implementation have been improved and made more logical. For example, filters have been replaced with pipes, which is a more intuitive and logical syntax.

Data binding and templates are the heart of Angular 2, allowing you to create dynamic and interactive user interfaces.

Templates are used to represent the view part of a component and can be augmented with new syntax and behavior to enable things like interpolation and two-way data binding.

You can use interpolation to display a component's property in a view, like this: {{helloWorld}}.

Property binding lets you pass data between parent and child components, for example [person]=selectedPerson sends the selectedPerson property in the parent to the person property in the child component.

Event binding lets you bind DOM events to methods within your component, like this: (click)=destroyUniverse().

Two-way data binding combines property and event binding into a single notation with [(ngModel)] and establishes a two-way data binding between template and component.

There are four types of data binding in Angular: interpolation, property binding, event binding, and two-way data binding.

Here are the different types of one-way data binding directed from the component to the view/template:

Two-way data binding lets you keep your view and underlying component in sync by updating the view whenever the component changes and vice versa, using the [(ngModel)] syntax.

Data binding is a powerful feature in Angular that lets you bind data and interaction between a template and a component in a declarative manner. Angular offers four types of data binding: interpolation, property binding, event binding, and two-way data binding.

Interpolation lets you display a component's property in a view, as seen in the example {{helloWorld}}. Property binding lets you pass data between parent and child components, for instance [person]=selectedPerson.

Event binding lets you bind DOM events to methods within your component, as shown in (click)=destroyUniverse(). Two-way data binding combines property and event binding into a single notation with [(ngModel)], establishing a two-way data binding between template and component.

You can create custom pipes by using the @Pipe decorator and implementing the PipeTransform interface, as mentioned in the section on Custom Pipes.

Use a single responsibility principle when structuring your code. This means each component should have one clear purpose.

Separate presentation from logic by using separate components for view and logic. This makes your code easier to read and maintain.

Use template-driven forms with caution, as they can lead to complex template code. Instead, use model-driven forms for better separation of concerns.

Avoid using ngIf and ngFor in the same template, as it can lead to performance issues. Use ngIf for conditional rendering and ngFor for list rendering.

Use the OnPush change detection strategy in your components to improve performance. This strategy only triggers change detection when the component's inputs change.

Use a consistent naming convention throughout your application. This makes your code easier to read and understand.

Avoid using the *ngIf directive to conditionally load modules. Instead, use a guard to conditionally load the module.

Angular Development is a breeze with the right tools. You can compile and serve an Angular 2 application via webpack or systemjs, but I've fallen in love with webpack.

Writing your Angular 2 application in TypeScript is the way to go, as it lends itself best to the framework and offers a tenfold return on investment in terms of productivity and clarity. You'll need to download the repository, run npm i to install the package dependencies, and then set up your TypeScript compilation.

In your packages.json file, you can define a task that uses webpack-dev-server along with webpack to bundle your TypeScript modules and other assets into a single javascript file and then serve the app.

Explore further: Next Js Webpack Config

To compile and serve an Angular 2 application, you have two main options: webpack or systemjs. I've personally fallen in love with webpack and will be using it to build this app.

You can write your Angular 2 application in ES5, EcmaScript 2015, or TypeScript, but the framework lends itself best to TypeScript. Writing in TypeScript requires a bit more setup, but the return on investment is tenfold in terms of productivity and clarity in our code.

To get started, download the repository and run npm i to install the package dependencies. We've defined how we want our TypeScript to be compiled, and now we need to create a hook for the work to be done.

In our packages.json file, we've defined a task that uses webpack-dev-server along with webpack to bundle our TypeScript modules and other assets into a single JavaScript file and then serve the app.

The code in App.ts may look weird, but it's actually TypeScript, a superset of JavaScript that adds optional static typing and other features.

In App.ts, you'll find the code that gets compiled into app.js, which is the JavaScript file that gets executed by the browser.

To compile App.ts into app.js, you'll need to use the 'tsc' script, which is located in the node_modules/.bin/ folder. You can execute this by typing $ ./node_modules/.bin/tsc, or use npm by typing $ npm run tsc.

The compilation process will generate app.js, which is the file that gets loaded by the browser. This is where the magic happens, and your Angular 2 application comes to life.

Worth a look: Npm Next Js

To get started with Angular 2, you'll need to configure your project with the right tools. One of the essential tools is TypeScript, which we'll use to compile our code into ES5 JavaScript.

The tsconfig.json file is crucial in telling our compiler how to compile our TypeScript files. We set the target to ES5 and the module to commonjs.

We also need to indicate how we want to generate our modules, and in this case, we're using the commonjs format. This will allow us to work seamlessly with our dependencies.

See what others are reading: Next Js Typescript

The tsconfig.json file is a crucial part of setting up your Angular project. It tells the compiler how to compile your TypeScript files.

We need to create a tsconfig.json file to tell our compiler how we want to compile our TypeScript files. This file is where we set the options for the compiler.

The tsconfig.json file needs to specify the target ECMAScript version, which in this case is ES5. We're also generating our modules in the commonjs format.

The tsconfig.json file has a few important properties, including "target" and "module". We're setting our ECMAScript version to ES5 and indicating that we want to generate our modules in the commonjs format.

The file below shows a sample tsconfig.json file. It's a good starting point, but we'll highlight the two most important properties: “target”: “ES5” and “module”: “commonjs”.

{

“compilerOptions”: {

“target”: “es5”,

“module”: “commonjs”,

“emitDecoratorMetadata”: true,

“experimentalDecorators”: true,

“sourceMap”: true,

“suppressImplicitAnyIndexErrors”:true

},

“compileOnSave”: false,

“buildOnSave”: false,

“exclude”: [

“node_modules”

],

“filesGlob”: [

“app/**/*.ts”,

“typings/browser.d.ts”

],

“atom”: {

“rewriteTsconfig”: false

}

}

Here's an interesting read: Nextjs Versions

When working with Angular, it's essential to understand the file structure.

Download the sample-ng2.zip file or copy/paste the code to get started. The file structure will be a good starting point.

The file structure consists of three main files: index.html, ng2/app.ts, and ng2/package.json.

Angular Communication is a crucial aspect of building robust and scalable applications.

You can communicate between components using @Input and @Output decorators.

@Input properties allow a parent controller to pass data into a child controller. You can use this to pass a person to the PersonComponent from a parent component.

@Output events enable a child controller to communicate with its parent, passing data back up the component tree.

You can subscribe to the changed event in the parent component.

Here's a breakdown of the communication components: