Angular 2 - The component template


When angular finds a match in the DOM for a component selector, it will inject the component markup into that DOM element that it found a match on. 
The markup it will inject comes from the component metadata template properties.
 There are two options, the template, and the templateUrl.

For Ex: In the app component, we can see that it is using the template property and setting it to a string value of some markup. This is an inline template. The markup is declared within the component metadata. If we switch over to the browser, and take a look at the run time results by inspecting the DOM, we can see that the element named mw-app has the markup from the metadata inserted inside of it. Back in the code, we can change that markup in the template metadata property. Add some new content, like a p tag, with a description of what the media tracker app is all about, and when the browser reloads, we can see that our new content is there. 

Using template:


import { Component } from '@angular/core';

@Component({
  selector: 'app',
  template: '<h1>My App</h1>'
})
export class AppComponent {}


Using the template metadata property is an easy way to compose our angular components. And since we are writing our JavaScript using TypeScript, we can leverage future forward syntax, like the back tick to surround strings. ES2015 has support for back ticks which allow multi-line string definitions in JavaScript. So, we can use back ticks around the template value, and start moving things to multiple lines for better readability. The other metadata property we can use is the templateUrl. This property allows us to specify a file that contains the template content. Angular will load that template file for us, and do the same content injection. We can create a new file named app.component.html in the app folder to hold the template. And we can grab the markup from the template property and paste it into the new file. Then we can go back to the app.component.ts file and change the template property to be templateUrl. And give it the path to the app.component.html file we just created. Now this path is the relative path to the file from the base path of the web application served up by the web server. For this project, the web server is serving the files out of the root folder. Thus, the web path in this case is app/app.component.html. 

Using templateUrl :


import { Component } from '@angular/core';
                                                                                                                              
@Component({
  selector: 'mw-app',
  templateUrl: 'app/app.component.html'
})
export class AppComponent {}