title: In Angular 4 the hook ngOnChanges is not firing on input
body: <p>I am pretty new to Angular2/4. I have created a basic component with an input field. The user input will be reflected in the other components that are bound to the user input. Now I want to setup a general listener to a value change. </p>
  
  <p>I thought the OnChanges hook would be the perfect solution but ngOnChanges method was NEVER called. Am I doing something wrong?</p>
  
  <p>Any hint appreciated...</p>
  
  <pre><code>import { Component, Input, SimpleChanges, OnChanges } from '@angular/core';
  
  @Component({
    selector: 'my-app',
    template: `
      &lt;input [(ngModel)]="name"&gt;
      &lt;input [(ngModel)]="name"&gt;
      &lt;h1&gt;{{name}}&lt;/h1&gt;
    `,
  })
  export class AppComponent implements OnChanges {
  
    @Input() name: String = "abc"
  
    ngOnChanges(changes: SimpleChanges) {
      // changes.prop contains the old and the new value...
      console.log('on change', changes)
    }    
  
  }
  </code></pre>