let hub = () => ({
  hub: Object.create(null),
  emit(event, data) {
    (this.hub[event] || []).forEach((handler) => handler(data));
  },
  on(event, handler) {
    if (!this.hub[event]) this.hub[event] = [];
    this.hub[event].push(handler);
  },
  off(event, handler) {
    const i = (this.hub[event] || []).findIndex((h) => h === handler);
    if (i > -1) this.hub[event].splice(i, 1);
    if (this.hub[event].length === 0) delete this.hub[event];
  },
});

//Get hash of a given url

var some_url = 'https://usefulangle.com/posts?123#slider'

var hash = new URL(some_url).hash;

// "#slider"
console.log(hash);

//
//
//


//Get hash of the current url

// document.URL refers to the current url
var hash = new URL(document.URL).hash;

console.log(hash);



//
//
//


//Change hash of a given url

var some_url = 'https://usefulangle.com/posts?123#slider'

var url_ob = new URL(some_url);
url_ob.hash = '#reviews';

// new url string
var new_url = url_ob.href;

// "https://usefulangle.com/posts?123#reviews"
console.log(new_url);


//
//
//


//Change hash of the current url

// document.URL is the current url
var url_ob = new URL(document.URL);
url_ob.hash = '#345';

// new url
var new_url = url_ob.href;

// change the current url
document.location.href = new_url;


//
//
//

/*
Detecting Change in Hash of the Current URL

The window.hashchange event can be listened to know when the hash fragment in the current url changes.
*/

window.addEventListener('hashchange', function() {
	// new hash value
	console.log(new URL(document.URL).hash);
});

$( ".variations_form" ).on( "woocommerce_variation_select_change", function () {
    // Fires whenever variation selects are changed
} );

$( ".single_variation_wrap" ).on( "show_variation", function ( event, variation ) {
    // Fired when the user selects all the required dropdowns / attributes
    // and a final variation is selected / shown
} );

// The keys and notes variables store the piano keys
const keys = ['c-key', 'd-key', 'e-key', 'f-key', 'g-key', 'a-key', 'b-key', 'high-c-key', 'c-sharp-key', 'd-sharp-key', 'f-sharp-key', 'g-sharp-key', 'a-sharp-key'];
/* */
const notes = [];
keys.forEach(function(key){
  notes.push(document.getElementById(key));
})
// Write named functions that change the color of the keys below
const keyPlay = (event) => {
  event.target.style.backgroundColor = 'blue';
};
const keyReturn = (event) => {
  event.target.style.backgroundColor = '';
};
// Write a named function with event handler properties
const eventAssignment = (note) => {
  note.onmousedown = () => {
    keyPlay(event);
  }
  note.onmouseup = () => {
    keyReturn(event);
  }
};
// Write a loop that runs the array elements through the function
notes.forEach(eventAssignment);
// These variables store the buttons that progress the user through the lyrics
let nextOne = document.getElementById('first-next-line');
let nextTwo = document.getElementById('second-next-line');
let nextThree = document.getElementById('third-next-line');
let startOver = document.getElementById('fourth-next-line');
// This variable stores the '-END' lyric element
let lastLyric = document.getElementById('column-optional');
// These statements are "hiding" all the progress buttons, but the first one
nextTwo.hidden = true;
nextThree.hidden = true;
startOver.hidden= true;
// Write anonymous event handler property and function for the first progress button
nextOne.onclick = () => {
  nextTwo.hidden = false;
  nextOne.hidden = true;
  /* */
  document.getElementById('letter-note-five').innerHTML = 'D';
  document.getElementById('letter-note-six').innerHTML = 'C';
};
// Write anonymous event handler property and function for the second progress button
nextTwo.onclick = () => {
  nextThree.hidden = false;
  nextTwo.hidden = true;
  /* */
  document.getElementById('word-five').innerHTML = 'DEAR';
  document.getElementById('word-six').innerHTML = 'FRI-';
  /* */
  lastLyric.style.display = 'inline-block';
  /* */
  document.getElementById('letter-note-three').innerHTML = 'G';
  document.getElementById('letter-note-four').innerHTML = 'E';
  document.getElementById('letter-note-five').innerHTML = 'C';
  document.getElementById('letter-note-six').innerHTML = 'B';
};
// Write anonymous event handler property and function for the third progress button
nextThree.onclick = () => {
  startOver.hidden = false;
  nextThree.hidden = true;
  /* */
  document.getElementById('word-one').innerHTML = 'HAP-';
  document.getElementById('word-two').innerHTML = 'PY';
  document.getElementById('word-three').innerHTML = 'BIRTH';
  document.getElementById('word-four').innerHTML = 'DAY';
  document.getElementById('word-five').innerHTML = 'TO';
  document.getElementById('word-six').innerHTML = 'YOU!';
  /* */
  document.getElementById('letter-note-one').innerHTML = 'F';
  document.getElementById('letter-note-two').innerHTML = 'F';
  document.getElementById('letter-note-three').innerHTML = 'E';
  document.getElementById('letter-note-four').innerHTML = 'C';
  document.getElementById('letter-note-five').innerHTML = 'D';
  document.getElementById('letter-note-six').innerHTML = 'C';
  /* */
  lastLyric.style.display = 'none';
};

// This is the event handler property and function for the startOver button
startOver.onclick = function() {
  nextOne.hidden = false;
  startOver.hidden = true;
   document.getElementById('word-one').innerHTML = 'HAP-';
  document.getElementById('letter-note-one').innerHTML = 'G';
  document.getElementById('word-two').innerHTML = 'PY';
  document.getElementById('letter-note-two').innerHTML = 'G';
  document.getElementById('word-three').innerHTML = 'BIRTH-';
  document.getElementById('letter-note-three').innerHTML = 'A';
  document.getElementById('word-four').innerHTML = 'DAY';
  document.getElementById('letter-note-four').innerHTML = 'G';
  document.getElementById('word-five').innerHTML = 'TO';
  document.getElementById('letter-note-five').innerHTML = 'C';
  document.getElementById('word-six').innerHTML = 'YOU!';
  document.getElementById('letter-note-six').innerHTML = 'B';
};