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@ -1,7 +1,7 @@
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include ../../../_includes/_util-fns
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:marked
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Let's start from zero and build a simple Angular 2 application in JavaScript.
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Let's start from zero and build a super simple Angular 2 application in JavaScript.
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.callout.is-helpful
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header Don't want JavaScript?
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@ -9,188 +9,474 @@ include ../../../_includes/_util-fns
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Although we're getting started in JavaScript, you can also write Angular 2 apps
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in TypeScript and Dart by selecting either of those languages from the combo-box in the banner.
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.l-main-section
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:marked
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## See It Run!
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Running the [live example](/resources/live-examples/quickstart/js/plnkr.html)
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is the quickest way to see an Angular 2 app come to life.
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Clicking that link fires up a browser, loads the sample in [plunker](http://plnkr.co/ "Plunker"),
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and displays a simple message:
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figure.image-display
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img(src='/resources/images/devguide/quickstart/my-first-app.png' alt="Output of quickstart app")
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:marked
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Here is the file structure:
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code-example(format="").
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angular2-quickstart
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├─ app
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│ ├── app.component.js
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│ └── boot.js
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├─ index.htm
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└─ license.md
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:marked
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Functionally, it's an `index.html` and two JavaScript files in an `app/` folder.
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We can handle that!
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Of course we won't build many apps that only run in plunker.
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Let's follow a process that's closer to what we'd do in real life.
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1. Set up our development environment
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1. Write the Angular root component for our app
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1. Bootstrap it to take control of the main web page
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1. Write the main page (`index.html`)
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.l-sub-section
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:marked
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We really can build the QuickStart from scratch in five minutes
|
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if we follow the instructions and ignore the commentary.
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Most of us will be interested in the "why" as well as the "how" and that will take longer.
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:marked
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We'll do it in six short steps
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1. Create a project folder
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1. Install essential libraries
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1. Write the root component for our application in *app.js*
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1. Bootstrap the app
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1. Create an *index.html*
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1. Run it
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.l-main-section
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:marked
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## Development Environment
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We'll need a place to stand (the application project folder), some libraries,
|
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|
some TypeScript configuration and the TypeScript-aware editor of your choice.
|
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|
|
|
|
|
|
### Create a new project folder
|
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|
code-example(format="").
|
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mkdir angular2-quickstart
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|
cd angular2-quickstart
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:marked
|
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|
|
### Add the libraries we need
|
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We recommend the **npm** package manager for acquiring and managing our development libraries.
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.l-sub-section
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:marked
|
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|
|
## Create a project folder
|
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|
|
Don't have npm?
|
|
|
|
|
[Get it now](https://docs.npmjs.com/getting-started/installing-node "Installing Node.js and updating npm")
|
|
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|
|
because we're going to use it now and repeatedly throughout this documentation.
|
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|
|
:marked
|
|
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|
|
Add a **package.json** file to the project folder and copy/paste the following:
|
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|
|
+makeJson('quickstart/js/package.1.json', null, 'package.json')(format=".")
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|
|
**Create a new folder** to hold our application project, perhaps like this:
|
|
|
|
|
```
|
|
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|
|
mkdir angular2-quickstart
|
|
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|
|
cd angular2-quickstart
|
|
|
|
|
```
|
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|
.l-main-section
|
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|
.l-sub-section
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:marked
|
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|
|
## Install essential libraries
|
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|
|
We'll use the **npm package manager** to install packages for
|
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|
|
the libraries and development tools we need:
|
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|
|
>angular2 - the Angular 2 library.
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|
|
>[live-server](https://www.npmjs.com/package/live-server "Live-server")
|
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|
|
a static file server that reloads the browser when files change.
|
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|
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|
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|
|
We could reference the libraries on the web or download them to our project.
|
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|
|
That isn't a sustainable development process and package loading with npm is really
|
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|
|
easy once we have it installed.
|
|
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|
|
|
.alert.is-helpful
|
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|
|
:marked
|
|
|
|
|
Don't have npm? [Get it now](https://docs.npmjs.com/getting-started/installing-node "Installing Node.js and updating npm")
|
|
|
|
|
because we're going to use it now and repeatedly throughout this documentation.
|
|
|
|
|
|
|
|
|
|
Itching to know the details? We explain in the [appendix below](#package-json)
|
|
|
|
|
:marked
|
|
|
|
|
Install these packages by opening a terminal window (command window in Windows) and
|
|
|
|
|
running this npm command.
|
|
|
|
|
code-example(format="").
|
|
|
|
|
npm install
|
|
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|
|
:marked
|
|
|
|
|
.l-sub-section
|
|
|
|
|
:marked
|
|
|
|
|
**Open** a terminal window and enter these commands:
|
|
|
|
|
```
|
|
|
|
|
npm init -y
|
|
|
|
|
npm i angular2@2.0.0-alpha.44 --save --save-exact
|
|
|
|
|
npm i live-server --save-dev
|
|
|
|
|
```
|
|
|
|
|
These commands both *install* the packages and *create* an npm configuration
|
|
|
|
|
file named `package.json`.
|
|
|
|
|
The essence of our `package.json` should look like this:
|
|
|
|
|
|
|
|
|
|
+makeJson('quickstart/js/package.1.json', { paths: 'name, version, dependencies, devDependencies'})
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
There is also a `scripts` section. **Find and replace** it with the following:
|
|
|
|
|
|
|
|
|
|
+makeJson('quickstart/js/package.1.json', { paths: 'scripts'})
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
We've just extended our project world with a script command that we'll be running very soon.
|
|
|
|
|
Scary <span style="color:red; font-weight: bold">error messages in red</span> may appear **during** install.
|
|
|
|
|
Ignore them. The install will succeed. See the [appendix below](#npm-errors) for more information.
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
## Our First Angular Component
|
|
|
|
|
|
|
|
|
|
The *Component* is the most fundamental of Angular concepts.
|
|
|
|
|
A component manages a view - a piece of the web page where we display information
|
|
|
|
|
to the user and respond to user feedback.
|
|
|
|
|
|
|
|
|
|
Technically, a component is a class that controls a view template.
|
|
|
|
|
We'll write a lot of them as we build Angular apps. This is our first attempt
|
|
|
|
|
so we'll keep it ridiculously simple.
|
|
|
|
|
|
|
|
|
|
### Create an application source sub-folder
|
|
|
|
|
|
|
|
|
|
We like to keep our application code in a sub-folder off the root called `app/`.
|
|
|
|
|
Execute the following command in the console window.
|
|
|
|
|
code-example(format="").
|
|
|
|
|
mkdir app
|
|
|
|
|
cd app
|
|
|
|
|
:marked
|
|
|
|
|
### Add the component file
|
|
|
|
|
Now add a file named **app.component.js** and paste the following lines:
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', null, 'app/app.component.js')(format=".")
|
|
|
|
|
:marked
|
|
|
|
|
We're creating a visual component named **`AppComponent`** by chaining the
|
|
|
|
|
`Component` and `Class` methods that belong to the **global Angular core namespace, `ng.core`**.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', 'ng-namespace-funcs', 'app/component.js (Angular 2 methods)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
The **`Component`** method takes a configuration object with two
|
|
|
|
|
properties. The **`Class`** method is where we implement the component itself,
|
|
|
|
|
giving it properties and methods that bind to the view and whatever
|
|
|
|
|
behavior is appropriate for this part of the UI.
|
|
|
|
|
|
|
|
|
|
Let's review this file in detail.
|
|
|
|
|
|
|
|
|
|
### Modules
|
|
|
|
|
Angular apps are modular. They consist of many files each dedicated to a purpose.
|
|
|
|
|
ES5 JavaScript doesn't have modules, but we don't want to pollute the global namespace.
|
|
|
|
|
|
|
|
|
|
So we'll surround the code in a simple IIFE ("Immediately Invoked Function Execution").
|
|
|
|
|
It receives our `app` 'namespace' object as argument.
|
|
|
|
|
We call our IIFE with `window.app` if it exists - and if it doesn't we
|
|
|
|
|
initialize it as an empty object.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', 'iife', 'app/component.js (IIFE)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
Most application files *export* one thing into our faux-pas 'namespace', such as a component.
|
|
|
|
|
Our `app.component.js` file exports the `AppComponent`.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', 'export', 'app/component.js (export)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
A more sophisticated application would have child components that descended from
|
|
|
|
|
`AppComponent` in a visual tree.
|
|
|
|
|
A more sophisticated app would have more files and modules, at least as many as it had components.
|
|
|
|
|
|
|
|
|
|
Quickstart isn't sophisticated; one component is all we need.
|
|
|
|
|
Yet modules play a fundamental organizational role in even this small app.
|
|
|
|
|
|
|
|
|
|
Modules rely on other modules. In JavaScript Angular apps, when we need something
|
|
|
|
|
provided by another module, we get it from the `app` object.
|
|
|
|
|
When another module needs to refer to `AppComponent`, it gets it from the `app.AppComponent` like this:
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/boot.js', 'import','app/boot.js (import)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
Angular is also modular. It is a collection of library modules.
|
|
|
|
|
Each library is itself a module made up of several, related feature modules.
|
|
|
|
|
|
|
|
|
|
When we need something from Angular, we use the `ng` object.
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
### The Class definition object
|
|
|
|
|
At the bottom of the file is an empty, do-nothing class definition object for
|
|
|
|
|
our `AppComponent` class.
|
|
|
|
|
When we're ready to build a substantive application,
|
|
|
|
|
we can expand this object with properties and application logic.
|
|
|
|
|
Our `AppComponent` class has nothing but an empty constructor because we
|
|
|
|
|
don't need it to do anything in this QuickStart.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', 'class','app.component.js (class)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
### The Component definition object
|
|
|
|
|
`ng.core.Component()` tells Angular that this class definition object
|
|
|
|
|
*is an Angular component*.
|
|
|
|
|
The configuration object passed to the `ng.core.Component()` method has two
|
|
|
|
|
fields, a `selector` and a `template`.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app/app.component.js', 'component','app.component.js (component)')(format=".")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
The `selector` specifies a simple CSS selector for a host HTML element named `my-app`.
|
|
|
|
|
Angular creates and displays an instance of our `AppComponent`
|
|
|
|
|
wherever it encounters a `my-app` element in the host HTML.
|
|
|
|
|
|
|
|
|
|
.alert.is-helpful
|
|
|
|
|
:marked
|
|
|
|
|
## Our first Angular component
|
|
|
|
|
|
|
|
|
|
Add a new file called *app.js* and paste the following lines:
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app.js', 'class-w-annotations')
|
|
|
|
|
Remember the `my-app` selector! We'll need that information when we write our `index.html`
|
|
|
|
|
:marked
|
|
|
|
|
The `template` property holds the component's companion template.
|
|
|
|
|
A template is a form of HTML that tells Angular how to render a view.
|
|
|
|
|
Our template is a single line of HTML announcing "My First Angular App".
|
|
|
|
|
|
|
|
|
|
Now we need something to tell Angular to load this component.
|
|
|
|
|
|
|
|
|
|
### Give it the boot
|
|
|
|
|
|
|
|
|
|
Add a new file , `boot.js`, to the `app/` folder as follows:
|
|
|
|
|
+makeExample('quickstart/js/app/boot.js', null, 'app/boot.js')(format=".")
|
|
|
|
|
:marked
|
|
|
|
|
We need two things to launch the application:
|
|
|
|
|
1. Angular's browser `bootstrap` function
|
|
|
|
|
1. The application root component that we just wrote.
|
|
|
|
|
|
|
|
|
|
We have them both in our 'namespaces'.
|
|
|
|
|
Then we call `bootstrap`, passing in the **root component type**, `AppComponent`.
|
|
|
|
|
|
|
|
|
|
.l-sub-section
|
|
|
|
|
:marked
|
|
|
|
|
We're creating a visual component named **`AppComponent`** by chaining the
|
|
|
|
|
`Component` and `Class` methods that belong to the **global Angular namespace, `ng`**.
|
|
|
|
|
|
|
|
|
|
```
|
|
|
|
|
var AppComponent = ng
|
|
|
|
|
.Component({...})
|
|
|
|
|
.Class({...})
|
|
|
|
|
```
|
|
|
|
|
The **`Component`** method takes a configuration object with two
|
|
|
|
|
properties. The `selector` property tells Angular that this is a component
|
|
|
|
|
controlling a host element named "my-app".
|
|
|
|
|
Angular creates and displays an instance of our `AppComponent`
|
|
|
|
|
wherever it encounters a `my-app` element.
|
|
|
|
|
|
|
|
|
|
The `template` property defines the visual appearance of the component.
|
|
|
|
|
We're writing the HTML template inline in this example.
|
|
|
|
|
Later we'll move the HTML to a view template file and
|
|
|
|
|
assign the template's filename to the `templateUrl` property.
|
|
|
|
|
We'll prefer that practice for all but the most trivial templates.
|
|
|
|
|
|
|
|
|
|
The **`Class`** method is where we implement the component itself,
|
|
|
|
|
giving it properties and methods that bind to the view and whatever
|
|
|
|
|
behavior is appropriate for this part of the UI.
|
|
|
|
|
|
|
|
|
|
This component class has the bare minimum implementation:
|
|
|
|
|
a *no-op* constructor function that does nothing because there is nothing to do.
|
|
|
|
|
We'll see more interesting component classes in future examples.
|
|
|
|
|
Learn why we need `bootstrap` from `ng.platform.browser`
|
|
|
|
|
and why we create a separate *boot.js* file in the [appendix below](#boot).
|
|
|
|
|
:marked
|
|
|
|
|
We've asked Angular to launch the app in a browser with our component at the root.
|
|
|
|
|
Where will Angular put it?
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
## Bootstrap the app
|
|
|
|
|
We need to do something to put our application in motion.
|
|
|
|
|
Add the following to the bottom of the `app.js` file:
|
|
|
|
|
:marked
|
|
|
|
|
## Add the `index.html`
|
|
|
|
|
|
|
|
|
|
Angular displays our application in a specific location on our `index.html`.
|
|
|
|
|
It's time to create that file.
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/app.js', 'bootstrap')
|
|
|
|
|
We won't put our `index.html` in the `app/` folder.
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We'll locate it **up one level, in the project root folder**.
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code-example(format="").
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cd ..
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:marked
|
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Now create the`index.html` file and paste the following lines:
|
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|
+makeExample('quickstart/js/index.html', null, 'index.html')(format=".")
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:marked
|
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There are three noteworthy sections of HTML:
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:marked
|
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We'll wait for the browser to tell us that it has finished loading
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all content and then we'll call the Angular `bootstrap` method.
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|
|
1. We load the JavaScript libraries we need. `angular2-polyfills.js` and `Rx.js` are needed by Angular 2.<br/>
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|
The `bootstrap` method tells Angular to start the application with our
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|
`AppComponent` at the application root.
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We'd be correct to guess that someday our application will
|
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|
|
consist of more components arising in tree-like fashion from this root.
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2. We load our JavaScript files, paying attention to their order (`boot.js` needs `app.component.js` to be there first).
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|
### Wrapped in an IIFE
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We don't want to pollute the global namespace.
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We don't need an application namespace yet.
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So we'll surround the code in a simple IIFE
|
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("Immediately Invoked Function Execution")
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wrapper.
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Here is the entire file:
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|
+makeExample('quickstart/js/app.js', 'dsl')
|
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|
3. We add the `<my-app>` tag in the `<body>`. **This is where our app lives!**
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When Angular calls the `bootstrap` function in `boot.js`, it reads the `AppComponent`
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metadata, finds the `my-app` selector, locates an element tag named `my-app`,
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and loads our application between those tags.
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.l-main-section
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:marked
|
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|
## Compile and run!
|
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|
Open a terminal window and enter this command:
|
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|
code-example(format="").
|
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|
npm start
|
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|
|
:marked
|
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|
|
That command runs a static server called **lite-server** that loads `index.html` in a browser
|
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|
|
and refreshes the browser when application files change.
|
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|
In a few moments, a browser tab should open and display
|
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|
|
figure.image-display
|
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|
|
img(src='/resources/images/devguide/quickstart/my-first-app.png' alt="Output of quickstart app")
|
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:marked
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|
Congratulations! We are in business.
|
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|
.alert.is-helpful
|
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:marked
|
|
|
|
|
## Create an *index.html*
|
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|
|
If you see `Loading...` displayed instead, see the
|
|
|
|
|
[Browser ES6 support appendix](#es6support).
|
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|
|
:marked
|
|
|
|
|
### Make some changes
|
|
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|
|
Try changing the message to "My SECOND Angular 2 app".
|
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|
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|
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|
|
`lite-server` is watching, so it should detect the change,
|
|
|
|
|
refresh the browser, and display the revised message.
|
|
|
|
|
|
|
|
|
|
**Add a new `index.html`** file to the project folder and enter the following HTML
|
|
|
|
|
|
|
|
|
|
+makeExample('quickstart/js/index.html', null, 'index.html')(format="")
|
|
|
|
|
.l-sub-section
|
|
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|
|
:marked
|
|
|
|
|
Our app loads two script files in the `<head>` element:
|
|
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|
|
|
|
|
|
|
>***angular2.sfx.dev.js***, the Angular 2 development library that puts
|
|
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|
|
Angular in the global `ng` namespace.
|
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|
|
|
|
|
|
|
|
>***app.js***, the application JavaScript we just wrote.
|
|
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|
|
|
|
|
|
In the `<body>`, there's an element called `<my-app>`.
|
|
|
|
|
This is the placeholder for the *root* of the
|
|
|
|
|
application. Angular displays our application here.
|
|
|
|
|
It's a nifty way to develop an application!
|
|
|
|
|
|
|
|
|
|
We close the terminal window when we're done to terminate the server.
|
|
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|
|
|
|
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|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
## Final structure
|
|
|
|
|
Our final project folder structure looks like this:
|
|
|
|
|
code-example(format="").
|
|
|
|
|
angular2-quickstart
|
|
|
|
|
├── node_modules
|
|
|
|
|
├── app
|
|
|
|
|
│ ├── app.component.js
|
|
|
|
|
| └── boot.js
|
|
|
|
|
├── index.html
|
|
|
|
|
├── package.json
|
|
|
|
|
└── tsconfig.json
|
|
|
|
|
:marked
|
|
|
|
|
And here are the files:
|
|
|
|
|
+makeTabs(`
|
|
|
|
|
quickstart/js/app/app.component.js,
|
|
|
|
|
quickstart/js/app/boot.js,
|
|
|
|
|
quickstart/js/index.html,
|
|
|
|
|
quickstart/js/package.1.json
|
|
|
|
|
`,null,
|
|
|
|
|
`app/app.component.js, app/boot.js, index.html,package.json`)
|
|
|
|
|
:marked
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
## Wrap Up
|
|
|
|
|
Our first application doesn't do much. It's basically "Hello, World" for Angular 2.
|
|
|
|
|
|
|
|
|
|
We kept it simple in our first pass: we wrote a little Angular component,
|
|
|
|
|
we added some JavaScript libraries to `index.html`, and launched with a
|
|
|
|
|
static file server. That's about all we'd expect to do for a "Hello, World" app.
|
|
|
|
|
|
|
|
|
|
**We have greater ambitions.**
|
|
|
|
|
|
|
|
|
|
The good news is that the overhead of setup is (mostly) behind us.
|
|
|
|
|
We'll probably only touch the `package.json` to update libraries.
|
|
|
|
|
Besides adding in the script files for our app 'modules',
|
|
|
|
|
we'll likely open `index.html` only if we need to add a library or some css stylesheets.
|
|
|
|
|
|
|
|
|
|
We're about to take the next step and build a small application that
|
|
|
|
|
demonstrates the great things we can build with Angular 2.
|
|
|
|
|
|
|
|
|
|
Join us on the [Tour of Heroes Tutorial](./tutorial)!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
## Appendices
|
|
|
|
|
The balance of this chapter is a set of appendices that
|
|
|
|
|
elaborate some of the points we covered quickly above.
|
|
|
|
|
|
|
|
|
|
There is no essential material here. Continued reading is for the curious.
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
<a id="es6support"></a>
|
|
|
|
|
### Appendix: Browser ES6 support
|
|
|
|
|
Angular 2 relies on some ES2015 features, most of them found in modern
|
|
|
|
|
browsers. Some browsers (including IE 11) require a shim to support the
|
|
|
|
|
the needed functionality.
|
|
|
|
|
Try loading the following shim *above* the other scripts in the `index.html`:
|
|
|
|
|
|
|
|
|
|
code-example(language="html" format=".").
|
|
|
|
|
<script src="node_modules/es6-shim/es6-shim.js"></script>
|
|
|
|
|
:marked
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
<a id="package-json"></a>
|
|
|
|
|
### Appendix: package.json
|
|
|
|
|
|
|
|
|
|
[npm](https://docs.npmjs.com/) is a popular package manager and Angular application developers rely on it
|
|
|
|
|
to acquire and manage the libraries their apps require.
|
|
|
|
|
|
|
|
|
|
We specify the packages we need in an npm [package.json](https://docs.npmjs.com/files/package.json) file.
|
|
|
|
|
|
|
|
|
|
The Angular team suggests the packages listed in the `dependencies` and `devDependencies`
|
|
|
|
|
sections listed in this file:
|
|
|
|
|
|
|
|
|
|
+makeJson('quickstart/js/package.1.json',{ paths: 'dependencies, devDependencies'}, 'package.json (dependencies)')(format=".")
|
|
|
|
|
:marked
|
|
|
|
|
.l-sub-section
|
|
|
|
|
:marked
|
|
|
|
|
## Run it!
|
|
|
|
|
There are other possible package choices.
|
|
|
|
|
We're recommending this particular set that we know work well together.
|
|
|
|
|
Play along with us for now.
|
|
|
|
|
Feel free to make substitutions later to suit your tastes and experience.
|
|
|
|
|
:marked
|
|
|
|
|
A `package.json` has an optional **scripts** section where we can define helpful
|
|
|
|
|
commands to perform development and build tasks.
|
|
|
|
|
We've included a number of such scripts in our suggested `package.json`:
|
|
|
|
|
+makeJson('quickstart/js/package.1.json',{ paths: 'scripts'}, 'package.json (scripts)')(format=".")
|
|
|
|
|
:marked
|
|
|
|
|
We've seen how we can run the server with this command:
|
|
|
|
|
code-example(format="").
|
|
|
|
|
npm start
|
|
|
|
|
:marked
|
|
|
|
|
We are using the special `npm start` command, but all it does is run `npm run lite`.
|
|
|
|
|
|
|
|
|
|
We execute npm scripts in that manner: `npm run` + *script-name*. Here's what these scripts do:
|
|
|
|
|
|
|
|
|
|
* `npm run lite` - run the [lite-server](https://www.npmjs.com/package/lite-server),
|
|
|
|
|
a light-weight, static file server, written and maintained by [John Papa](http://johnpapa.net/)
|
|
|
|
|
with excellent support for Angular apps that use routing.
|
|
|
|
|
|
|
|
|
|
We need a file server to serve the static assets of our application
|
|
|
|
|
(*index.html* and *app.js*).
|
|
|
|
|
|
|
|
|
|
For this example we'll use the **live-server** that we installed with `npm`
|
|
|
|
|
because it performs a live reload by default and it's
|
|
|
|
|
fun to watch the browser update as we make changes.
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
<a id="npm-errors"></a>
|
|
|
|
|
### Appendix: Npm errors and warnings
|
|
|
|
|
|
|
|
|
|
All is well if there are no console messages starting with `npm ERR!` *at the end* of an **npm install**.
|
|
|
|
|
There might be a few `npm WARN` messages along the way — and that is perfectly fine.
|
|
|
|
|
|
|
|
|
|
We often see an `npm WARN` message after a series of `gyp ERR!` messages.
|
|
|
|
|
Ignore them. A package may try to re-compile itself using `node-gyp`.
|
|
|
|
|
If the re-compile fails, the package recovers (typically with a pre-built version)
|
|
|
|
|
and everything works.
|
|
|
|
|
|
|
|
|
|
We are in good shape as long as there are no `npm ERR!` messages at the very end of `npm install`.
|
|
|
|
|
|
|
|
|
|
.l-main-section
|
|
|
|
|
:marked
|
|
|
|
|
<a id="boot"></a>
|
|
|
|
|
### Appendix: ***boot.js***
|
|
|
|
|
|
|
|
|
|
Open a terminal (or Windows/Linux command line) and enter:
|
|
|
|
|
#### Bootstrapping is platform-specific
|
|
|
|
|
We use the `bootstrap` function from `ng.platform.browser`,
|
|
|
|
|
not `ng.core`. There's a good reason.
|
|
|
|
|
|
|
|
|
|
We only call "core" those capabilities that are the same across all platform targets.
|
|
|
|
|
True, most Angular applications run only in a browser and we'll call the bootstrap function from
|
|
|
|
|
this library most of the time. It's pretty "core" if we're always writing for a browser.
|
|
|
|
|
|
|
|
|
|
But it is possible to load a component in a different enviroment.
|
|
|
|
|
We might load it on a mobile device with [Apache Cordova](https://cordova.apache.org/)
|
|
|
|
|
We might wish to render the first page of our application on the server
|
|
|
|
|
to improve launch performance or facilitate
|
|
|
|
|
[SEO](http://static.googleusercontent.com/media/www.google.com/en//webmasters/docs/search-engine-optimization-starter-guide.pdf).
|
|
|
|
|
|
|
|
|
|
pre.prettyprint.lang-bash
|
|
|
|
|
code npm start
|
|
|
|
|
|
|
|
|
|
.alert.is-helpful
|
|
|
|
|
:marked
|
|
|
|
|
That's the `npm` command we added earlier to the `scripts` section of `package.json`
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
**live-server** loads the browser for us and refreshes the page as we make
|
|
|
|
|
changes to the application.
|
|
|
|
|
|
|
|
|
|
In a few moments, a browser tab should open and display
|
|
|
|
|
|
|
|
|
|
figure.image-display
|
|
|
|
|
img(src='/resources/images/devguide/quickstart/my-first-app.png' alt="Output of quickstart app")
|
|
|
|
|
|
|
|
|
|
:marked
|
|
|
|
|
### Make some changes
|
|
|
|
|
The `live-server` detects changes to our files and refreshes the browser page for us automatically.
|
|
|
|
|
|
|
|
|
|
Try changing the message to "My SECOND Angular 2 app".
|
|
|
|
|
The `live-server` sees that change and reloads the browser.
|
|
|
|
|
|
|
|
|
|
Keep `live-server` running in this terminal window and keep trying changes.
|
|
|
|
|
You can stop it anytime with `Ctrl-C`.
|
|
|
|
|
|
|
|
|
|
**Congratulations! We are in business** ... and ready to take
|
|
|
|
|
our app to the next level.
|
|
|
|
|
These targets require a different kind of bootstrap function that we'd import from a different library.
|
|
|
|
|
|
|
|
|
|
#### Why do we create a separate ***boot.js*** file?
|
|
|
|
|
|
|
|
|
|
The *boot.js* file is tiny. This is just a QuickStart.
|
|
|
|
|
We could have folded its few lines into the `app.component.js` file
|
|
|
|
|
and spared ourselves some complexity.
|
|
|
|
|
|
|
|
|
|
We didn't for what we believe to be good reasons:
|
|
|
|
|
1. Doing it right is easy
|
|
|
|
|
1. Testability
|
|
|
|
|
1. Reusability
|
|
|
|
|
1. Separation of concerns
|
|
|
|
|
1. We learned about import and export
|
|
|
|
|
|
|
|
|
|
#### It's easy
|
|
|
|
|
Sure it's an extra step and an extra file. How hard is that in the scheme of things?
|
|
|
|
|
|
|
|
|
|
We'll see that a separate `boot.js` is beneficial for *most* apps
|
|
|
|
|
even if it isn't critical for the QuickStart.
|
|
|
|
|
Let's develop good habits now while the cost is low.
|
|
|
|
|
|
|
|
|
|
#### Testability
|
|
|
|
|
We should be thinking about testability from the beginning
|
|
|
|
|
even if we know we'll never test the QuickStart.
|
|
|
|
|
|
|
|
|
|
It is difficult to unit test a component when there is a call to `bootstrap` in the same file.
|
|
|
|
|
As soon as we load the component file to test the component,
|
|
|
|
|
the `bootstrap` function tries to load the application in the browser.
|
|
|
|
|
It throws an error because we're not expecting to run the entire application,
|
|
|
|
|
just test the component.
|
|
|
|
|
|
|
|
|
|
Relocating the `bootstrap` function to `boot.js` eliminates this spurious error
|
|
|
|
|
and leaves us with a clean component module file.
|
|
|
|
|
|
|
|
|
|
#### Reusability
|
|
|
|
|
We refactor, rename, and relocate files as our application evolves.
|
|
|
|
|
We can't do any of those things while the file calls `bootstrap`.
|
|
|
|
|
we can't move it.
|
|
|
|
|
We can't reuse the component in another application.
|
|
|
|
|
We can't pre-render the component on the server for better performance.
|
|
|
|
|
|
|
|
|
|
#### Separation of concerns
|
|
|
|
|
A component's responsibility is to present and manage a view.
|
|
|
|
|
|
|
|
|
|
Launching the application has nothing to do with view management.
|
|
|
|
|
That's a separate concern. The friction we're encountering in testing and reuse
|
|
|
|
|
stems from this unnecessary mix of responsibilities.
|
|
|
|
|
|
|
|
|
|
#### Import/Export
|
|
|
|
|
|
|
|
|
|
While writing a separate `boot.js` file we learned an essential Angular skill:
|
|
|
|
|
how to 'export' from one 'module' and 'import' into another via our simple
|
|
|
|
|
namespace abstraction.
|
|
|
|
|
We'll do a lot of that as we learn more Angular.
|
|
|
|
|
|
Filipe Silva
Ward Bell