Add audio files for the metronome

src/Metronome.js

@@ -1,8 +1,11 @@
 import React, {Component} from 'react';
 import './Metronome.css';
+import click1 from './click1.wav';
+import click2 from './click2.wav';
 
 class Metronome extends Component {
     state;
+
     constructor(props) {
         super(props);
 
@@ -12,13 +15,22 @@ class Metronome extends Component {
             bpm: 100,
             beatsPerMeasure: 4
         };
+
+        // Create Audio objects with the files Webpack loaded,
+        // and we'll play them later.
+        this.click1 = new Audio(click1);
+        this.click2 = new Audio(click2);
     }
 
     handleBpmChange = event => {
         const bpm = event.target.value;
         this.setState({bpm});
     };
 
+    startStop = () => {
+        this.click1.play();
+    };
+
     render() {
         const {playing, bpm} = this.state;
 
@@ -33,7 +45,8 @@ class Metronome extends Component {
                         value={bpm}
                         onChange={this.handleBpmChange}/>
                 </div>
-                <button>
+                {/* Add the onClick handler: */}
+                <button onClick={this.startStop}>
                     {playing ? 'Stop' : 'Start'}
                 </button>
             </div>