title: Angular4 on change select box returns wrong value
body: <p>I want to do something in change event, but change event is returning a value with colon prefix. How to get correct value without prefix and colon?</p>
  
  <p><strong>education.component.html</strong></p>
  
  <pre><code>&lt;select class="form-control custom-select" name="course_id" id="course_id" formControlName="course_id" (change)="onChange($event.target.value)"&gt;
      &lt;option value=""&gt;--Select--&lt;/option&gt;
      &lt;option *ngFor="let course of course_list" [ngValue]="course.id"&gt;{{ course.name }}({{course.id}})&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p><strong>education.component.ts</strong></p>
  
  <pre><code>onChange(value) : void {
     console.log('Course Value',value)
  }
  </code></pre>
  
  <p><strong>For Example:</strong> I'm getting the value <strong>2:8</strong>. Expected value is <strong>8</strong></p>