Chart.js with Angular 2 - Can't capture label clicked on

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

@Component({
  selector: 'my-app',
  template: `<h4>How to get labels index when user clicks a label on y-axis?</h4>
  <div>
    # of Bars to draw: 
    <input type="number" placeholder="# of bars" style="width:35px"
      [(ngModel)]="numOfBars" (keydown.enter)="rebuildChart()"
    />
    <button (click)="rebuildChart()">Rebuild Chart</button>
    <span *ngIf="y_clicked!==null">Y-axis click value = {{y_clicked}}</span>
  </div>
  <hr/>
  <div><canvas #canvas></canvas></div>`
})
export class AppComponent implements AfterViewInit { 
  constructor(){}
  
  chart; //Chart.js instance
  @ViewChild('canvas') canvas; //Canvas tag.
  y_clicked = null; //holds y-axis .getValueForPixel() when chart is clicked
  timeoutID = null; //handle to setTimeout
  numOfBars = 5; //how many horizontal bars to chart
  
  ngAfterViewInit(){ //instantiates the chart
    this.chart = new Chart(
      this.canvas.nativeElement.getContext("2d"),
      this.getChartConfig()
    );
  }
  rebuildChart(){ //changes data and .updates() chart
    this.chart.config = this.getChartConfig();
    this.chart.update();
  }
  
  getChartConfig(){ //gets random data with which to fill the chart
    let dataSource = this.randomData(this.numOfBars);
    let data = {
      labels: dataSource.map(v=>v[0]),
      datasets:[{
        data: dataSource.map(v=>v[1])
      }],
    };
    let options = {
      legend:{display:false},
      title: {display:true,text:'Random chart title'},
      onClick:(clickEvt,activeElems)=>this.onChartClick(clickEvt,activeElems),
    };
    let type = 'horizontalBar';
    
    return {type:type,data:data,options:options};
  }
  
  randomData(count:number){ //gets array of specified length filled with random #s
    let results = [];
    for(let i=1; i <= +count; i++){
      //some values should be 0. The rest random.
      results.push([i,Math.random()<0.5 ? 0 : Math.random()])
    }
    return results;
  }
  onChartClick(clickEvt:MouseEvent,activeElems:Array<any>){
    //if click was on a bar, we don't care (we want clicks on labels)
    if(activeElems && activeElems.length) return;
    
    let mousePoint = Chart.helpers.getRelativePosition(clickEvt, this.chart.chart);
    let clickY = this.chart.scales['y-axis-0'].getValueForPixel(mousePoint.y);
    this.y_clicked = clickY;
    if(this.timeoutID) clearTimeout(this.timeoutID); //cancel any running timer
    this.timeoutID = setTimeout(()=>this.y_clicked=null,2000); //clear the value
  }
}


/*
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 { bootstrap }    from '@angular/platform-browser-dynamic';

import { AppComponent } from './app.component';

bootstrap(AppComponent);

let ScaleConstructor = chart.scaleService.getScaleConstructor("category");
ScaleConstructor.prototype.getValueForPixel = function(pixel) {
	var me = this;
	var value;
	var offsetAmt = Math.max((me.ticks.length - ((me.options.gridLines.offsetGridLines) ? 0 : 1)), 1);
	var horz = me.isHorizontal();
	var innerDimension = horz ? me.width - (me.paddingLeft + me.paddingRight) : me.height - (me.paddingTop + me.paddingBottom);
	var valueDimension = innerDimension / offsetAmt;

	pixel -= horz ? me.left : me.top;

	if (me.options.gridLines.offsetGridLines) {
		pixel -= (valueDimension / 2);
	}
	pixel -= horz ? me.paddingLeft : me.paddingTop;

	if (pixel <= 0) {
		value = 0;
	} else {
		value = Math.round(pixel / valueDimension);
	}

	return value;
};
/*
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
*/

/* Master Styles */
h1 {
  color: #369; 
  font-family: Arial, Helvetica, sans-serif;   
  font-size: 250%;
}
h2, h3 { 
  color: #444;
  font-family: Arial, Helvetica, sans-serif;   
  font-weight: lighter;
}
body { 
  margin: 2em; 
}
body, input[text], button { 
  color: #888; 
  font-family: Cambria, Georgia; 
}
a {
  cursor: pointer;
  cursor: hand;
}
button {
  font-family: Arial;
  background-color: #eee;
  border: none;
  padding: 5px 10px;
  border-radius: 4px;
  cursor: pointer;
  cursor: hand;
}
button:hover {
  background-color: #cfd8dc;
}
button:disabled {
  background-color: #eee;
  color: #aaa; 
  cursor: auto;
}

/* Navigation link styles */
nav a {
  padding: 5px 10px;
  text-decoration: none;
  margin-top: 10px;
  display: inline-block;
  background-color: #eee;
  border-radius: 4px;
}
nav a:visited, a:link {
  color: #607D8B;
}
nav a:hover {
  color: #039be5;
  background-color: #CFD8DC;
}
nav a.router-link-active {
  color: #039be5;
}

/* items class */
.items {
  margin: 0 0 2em 0;
  list-style-type: none;
  padding: 0;
  width: 24em;
}
.items li {
  cursor: pointer;
  position: relative;
  left: 0;
  background-color: #EEE;
  margin: .5em;
  padding: .3em 0;
  height: 1.6em;
  border-radius: 4px;
}
.items li:hover {
  color: #607D8B;
  background-color: #DDD;
  left: .1em;
}
.items li.selected:hover {
  background-color: #BBD8DC;
  color: white;
}
.items .text {
  position: relative;
  top: -3px;
}
.items {
  margin: 0 0 2em 0;
  list-style-type: none;
  padding: 0;
  width: 24em;
}
.items li {
  cursor: pointer;
  position: relative;
  left: 0;
  background-color: #EEE;
  margin: .5em;
  padding: .3em 0;
  height: 1.6em;
  border-radius: 4px;
}
.items li:hover {
  color: #607D8B;
  background-color: #DDD;
  left: .1em;
}
.items li.selected {
  background-color: #CFD8DC;
  color: white;
}

.items li.selected:hover {
  background-color: #BBD8DC;
}
.items .text {
  position: relative;
  top: -3px;
}
.items .badge {
  display: inline-block;
  font-size: small;
  color: white;
  padding: 0.8em 0.7em 0 0.7em;
  background-color: #607D8B;
  line-height: 1em;
  position: relative;
  left: -1px;
  top: -4px;
  height: 1.8em;
  margin-right: .8em;
  border-radius: 4px 0 0 4px;
}

/* everywhere else */
* { 
  font-family: Arial, Helvetica, sans-serif; 
}


/*
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
*/

<!DOCTYPE html>
<html>
  <head>
    <title>Angular 2 QuickStart</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="styles.css">
    
    <!-- Chart.js -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.1.6/Chart.min.js"></script>
    
    <!-- 1. Load libraries -->
     <!-- Polyfill(s) for older browsers -->
    <script src="https://npmcdn.com/core-js/client/shim.min.js"></script>

    <script src="https://npmcdn.com/zone.js@0.6.12?main=browser"></script>
    <script src="https://npmcdn.com/reflect-metadata@0.1.3"></script>
    <script src="https://npmcdn.com/systemjs@0.19.27/dist/system.src.js"></script>

    <!-- 2. Configure SystemJS -->
    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>

  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</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
-->

/**
 * PLUNKER VERSION (based on systemjs.config.js in angular.io)
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 */
(function(global) {

  var ngVer = '@2.0.0-rc.3'; // lock in the angular package version; do not let it float to current!
  var routerVer = '@3.0.0-alpha.7'; // lock router version
  var formsVer = '@0.1.1'; // lock forms version

  //map tells the System loader where to look for things
  var  map = {
    'app':                        'app',

    '@angular':                   'https://npmcdn.com/@angular', // sufficient if we didn't pin the version
    '@angular/router':            'https://npmcdn.com/@angular/router' + routerVer,
    '@angular/forms':             'https://npmcdn.com/@angular/forms' + formsVer,
    'angular2-in-memory-web-api': 'https://npmcdn.com/angular2-in-memory-web-api', // get latest
    'rxjs':                       'https://npmcdn.com/rxjs@5.0.0-beta.6',
    'ts':                         'https://npmcdn.com/plugin-typescript@4.0.10/lib/plugin.js',
    'typescript':                 'https://npmcdn.com/typescript@1.9.0-dev.20160409/lib/typescript.js',
 };

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

  var ngPackageNames = [
    'common',
    'compiler',
    'core',
    'http',
    'platform-browser',
    'platform-browser-dynamic',
    'router-deprecated',
    'upgrade',
  ];

  // Add map entries for each angular package
  // only because we're pinning the version with `ngVer`.
  ngPackageNames.forEach(function(pkgName) {
    map['@angular/'+pkgName] = 'https://npmcdn.com/@angular/' + pkgName + ngVer;
  });

  // Add package entries for angular packages
  ngPackageNames.forEach(function(pkgName) {

    // Bundled (~40 requests):
    packages['@angular/'+pkgName] = { main: '/bundles/' + pkgName + '.umd.js', defaultExtension: 'js' };

    // Individual files (~300 requests):
    //packages['@angular/'+pkgName] = { main: 'index.js', defaultExtension: 'js' };
  });

  // No umd for router yet
  packages['@angular/router'] = { main: 'index.js', defaultExtension: 'js' };

  // Forms not on rc yet
  packages['@angular/forms'] = { main: 'index.js', defaultExtension: 'js' };

  var config = {
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      tsconfig: true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    map: map,
    packages: packages
  };

  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
*/

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": true,
    "suppressImplicitAnyIndexErrors": true
  }
}