@HostBinding example using Angular2 RC4

<!DOCTYPE html>
<html>

  <head>
    <title>Angular2 RC4</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://npmcdn.com/zone.js@0.6.12"></script>
    <script src="https://npmcdn.com/reflect-metadata@0.1.3"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.27/system.js"></script>
    <script src="https://npmcdn.com/typescript@1.8.10/lib/typescript.js"></script>
    <script src="system.config.js"></script>
    <script>
    System.import('app')
      .catch(console.error.bind(console));
  </script>
  </head>

  <body>
    <my-app>
      Loading...
    </my-app>
  </body>

</html>

/* Styles go here */

/**
 * PLUNKER VERSION (based on systemjs.config.js in angular.io)
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 * Override at the last minute with global.filterSystemConfig (as plunkers do)
 */
(function(global) {

  var ngVer = '@2.0.0-rc.4'; // lock in the angular package version; do not let it float to current!

  //map tells the System loader where to look for things
  var  map = {
    'app':                        'src', // 'dist',
    'rxjs':                       'https://npmcdn.com/rxjs@5.0.0-beta.6',
    'angular2-in-memory-web-api': 'https://npmcdn.com/angular2-in-memory-web-api' // get latest
  };

  //packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'app.ts',  defaultExtension: 'ts' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { defaultExtension: 'js' },
  };

  var packageNames = [
      '@angular/common',
      '@angular/compiler',
      '@angular/core',
      '@angular/http',
      '@angular/platform-browser',
      '@angular/platform-browser-dynamic',
      '@angular/testing',
      '@angular/upgrade',
  ];

  // add map entries for angular packages in the form '@angular/common': 'https://npmcdn.com/@angular/common@0.0.0-3'
  packageNames.forEach(function(pkgName) {
    map[pkgName] = 'https://npmcdn.com/' + pkgName + ngVer;
  });

  // add package entries for angular packages in the form '@angular/common': { main: 'index.js', defaultExtension: 'js' }
  packageNames.forEach(function(pkgName) {
    packages[pkgName] = { main: 'index.js', defaultExtension: 'js' };
  });

  var config = {
    transpiler: 'typescript',
    typescriptOptions: {
      emitDecoratorMetadata: true
    },
    map: map,
    packages: packages
  }

  // filterSystemConfig - index.html's chance to modify config before we register it.
  if (global.filterSystemConfig) { global.filterSystemConfig(config); }

  System.config(config);

})(this);


/*
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

import {
  Component,
  Directive,
  provide,
  OnChanges,
  HostBinding,
  Input
} from '@angular/core';
import {bootstrap} from '@angular/platform-browser-dynamic';
import {Http, HTTP_PROVIDERS} from '@angular/http';

@Directive({
  selector: '[srcKey]'
})
export class SrcKeyDirective implements OnChanges {
  
  @Input() srcKey: string;
  @HostBinding() src;
  
  ngOnChanges() {
    this.src = `https://www.google.com.mt/images/branding/googlelogo/2x/${this.srcKey}_color_272x92dp.png`;
  }
}

@Component({
  selector: 'custom-img',
  template: `
    <img src="{{src}}">
  `
})
export class CustomImgComponent {
  @Input() src: string;
}

@Component({
  selector: 'my-app',
  directives: [CustomImgComponent, SrcKeyDirective],
  template: `
    Using img with SrcKeyDirective:<br/>
    <img [srcKey]="imageKey">
    <br/><br/>
    Using CustomImgComponent:<br/>
    <custom-img [src]="thisWorks"></custom-img>
    <br/><br/>
    Using CustomImgComponent with SrcKeyDirective:<br/>
    <custom-img [srcKey]="imageKey"></custom-img>
  `
})
export class AppComponent {
  imageKey = "googlelogo";
  thisWorks = `https://www.google.com.mt/images/branding/googlelogo/2x/${this.imageKey}_color_272x92dp.png`;
}

bootstrap(AppComponent, [
  HTTP_PROVIDERS,
])
  .catch(err => console.error(err));