(function DrumKit () {
const variables = {
className: 'playing',
keyEvent: 'keydown',
transitionEvent: 'transitionend',
};
function _addClass(element, name) {
element.classList.add(name);
}
function _removeClass(event) {
if (event.propertyName === 'transform') {
event.target.classList.remove(variables.className);
}
}
function _attachTransitionListener () {
Array
.from(document.querySelectorAll('.key'))
.forEach((key) => key.addEventListener(variables.transitionEvent, _removeClass));
}
function _playAudioFor (keyCode) {
const audioElement = document.querySelector(`audio[data-key="${keyCode}"]`);
if (audioElement !== null) {
audioElement.currentTime = 0;
audioElement.play();
}
}
function _toggleClassFor(keyCode) {
const divElement = document.querySelector(`div[data-key="${keyCode}"]`);
if (divElement !== null) {
_addClass(divElement, variables.className);
_attachTransitionListener();
}
}
function _initAudio (event) {
_playAudioFor(event.keyCode);
_toggleClassFor(event.keyCode);
}
function _attachListener () {
document.addEventListener(variables.keyEvent, _initAudio);
}
_attachListener();
}());