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Angular 4: Understanding Components
If you have followed my previous post on how to use angular-cli to generate an Angular app you may have noticed that it generated AppComponent as the root,in this post we will have a closer look at it to understand what a component is.
The simplest way to define a component is a class which is decorated with an attribute and has an html view which get rendered into the DOM.I have taken the AppComponent example to explain how it compares to a C# class.
It looks pretty close to ASP.NET MVC controller or any C# class with an attribute and it has a view called app.component.html which will get generated into the DOM.
The key thing is the @Component decorator takes a JSON anonymous object in which we specify the template URL and the custom styles to be used for this component. Here is an illustration of this.
And this is how the root component is wired up to the index.html page.
<body> <app-root>Loading...</app-root> </body>
Another interesting thing to notice is that the component has a property name “title” and by the virtual of the fact that a class is decorated with @Component attribute angular will allow you to bind this property to the view (template) using the double moustache syntax i.e. {{ }} which is also referred to as interpolation.
This is called one-way data binding as the data flows from the object to the view but not both ways, however it is easy to implement a two way by using the [(ngModel)] syntax as shown below.
<h1> {{title}} </h1> <input [(ngModel)]="title" />
After saving your changes and the page has refreshed if you type anything in the text box it will be immediately be reflected in the h1 header as shown below.
I hope this post has helped you if you are coming from a non angular background and to understand how thing works in angular.
Angular 2: Adding bootstrap css framework
In my previous post I showed you how to create an Angular 2 application using angular-cli tool. This post is a continuation of that and in this post I am going to show how to use node package manager npm to add bootstrap stylesheet and wire it up in the application.
I am going to open the nodejs command prompt and install the bootstrap css package to the project using the following command.
If you browse to the node_modules folder you can see the new folder bootstrap was created which contains all the stylesheets as shown below.
In order to make the stylesheet available for the page we have to add the path of the file to the styles array which is defined in the .angular-cli.json file. Since it is an array you can add multiple stylesheets and the loader will take care of it.
.angular-cli.json
"styles": [ "../node_modules/bootstrap/dist/css/bootstrap.min.css", "styles.css" ]
Now I am going to add some menu with the search text box and a jumbroton layout to give it a nice look.
<body> <nav class="navbar navbar-inverse"> <div class="container-fluid"> <div class="navbar-header"> <a class="navbar-brand" href="#">NG Corporationa> div> <ul class="nav navbar-nav"> <li class="active"><a href="#">Homea>li> <li><a href="#">Abouta>li> <li><a href="#">Servicea>li> <li><a href="#">Contacta>li> ul> <form class="navbar-form navbar-right"> <div class="input-group"> <input type="text" class="form-control" placeholder="Search"> <div class="input-group-btn"> <button class="btn btn-default" type="submit"> <i class="glyphicon glyphicon-search">i> button> div> div> form> div> nav> <div class="container"> <div class="row"> <div class="jumbotron"> <h1>NG Corporationh1> <p>A place to use your creativity, innovation and passion to build exciting product for the world.p> div> <app-root>Loading...app-root> div> div> body>
As you can see pretty standard bootstrap template and at the end we have our angular component with the custom selector “app-root”. Last thing we have to do is to run the following command in order to start the application.
And here is the angular 2 application up and running with bootstrap styling.
Getting started with Angular CLI
In this post I am going to show you how to install angular-cli and create a new Angular 2 application. It will be very useful if you are familiar with NodeJS, Node Package Manager(npm), TypeScript and Visual Studio Code (VSCode).
Lets get started with downloading NodeJs from https://nodejs.org/en/download/.
There are plenty of operating system to choose and since I am on Windows 10 64-bit, I am going to use the Windows Installer(.msi) 64-bit. This will install the nodejs runtime. Search and open the nodejs command prompt and install the angular-cli package using npm.
If you are using a proxy server then you might have to set the "https-proxy " value in the npm configuration as shown below.
and after a while you will see that the angular-cli installation was successful.
Lets check the version of the angular-cli by using the following command.
As you see I am using nodejs version 6.9.2 and angular-cli is in rc1 although the current version is rc2 which has been released a couple of days ago.
So after all the required installation I’m now going to create a new application helloworld using the angular-cli.
and you will see that the angular-cli has created a bunch of folders and files under the helloworld folder.
In order to run the application I’m going to use the ng serve command to run the application.
By default the application runs on port 4200 so lets browse to http://localhost:4200 and you can see the application is up and running and you can change the default port to any port by specifying the –p parameter to the ng serve command.
Lets open the project root folder using Visual Studio Code and modify the app.component.ts (TypeScript) file.
As soon as I change the title property of the AppComponent to "Hello world from Angular 2" the page automatically refreshes and shows my changes, I don’t have to hit F5 or refresh the page at all.
Congratulations you just created your first Angular 2 application using angular-cli.
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