import { Component, ViewChild, ElementRef, AfterContentInit } from '@angular/core';

@Component({
  selector: 'my-app',
  template: `
    <div  #target class="parent">
        <div class="child">
        </div>
    </div>
  `
})
export class AppComponent implements AfterContentInit {
    @ViewChild('target') elementRef: ElementRef;

    ngAfterContentInit(): void {
        var child = this.elementRef.nativeElement.querySelector('div');
        console.log(child);
    }
}
<!DOCTYPE html>
<html>
  <head>
    <title>Hello Angular</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <style>
      body {color:#369;font-family: Arial,Helvetica,sans-serif;}
    </style>

    <!-- Polyfills for older browsers -->
    <script src="https://unpkg.com/core-js/client/shim.min.js"></script>

    <script src="https://unpkg.com/zone.js@0.7.4?main=browser"></script>
    <script src="https://unpkg.com/reflect-metadata@0.1.8"></script>
    <script src="https://unpkg.com/systemjs@0.19.39/dist/system.src.js"></script>

    <script> window.autoBootstrap = true; </script>

    <script src="https://cdn.rawgit.com/angular/angular.io/b3c65a9/public/docs/_examples/_boilerplate/systemjs.config.web.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>

  <body>
    <my-app>Loading AppComponent content here ...</my-app>
  </body>

</html>


<!-- 
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
-->