index.js

var numberOfDrumButtons = document.querySelectorAll(".drum").length;
for (var i = 0; i < numberOfDrumButtons; i++) {

    document.querySelectorAll(".drum")[i].addEventListener("click", function () {
        var innerText = this.innerHTML;
        makeSound(innerText);
        buttonAnimation(innerText);
    });
}

document.addEventListener("keydown",function(event){
    makeSound(event.key);
    buttonAnimation(event.key);
} );




function makeSound(key) {
    switch (key) {
        case 'w':
            var tom1 = new Audio("sounds/tom-1.mp3");
            tom1.play();
            break;
        case 'a':
            var tom2 = new Audio("sounds/tom-2.mp3");
            tom2.play();
            break;
        case 's':
            var tom3 = new Audio("sounds/tom-3.mp3");
            tom3.play();
            break;
        case 'd':
            var tom4 = new Audio("sounds/tom-4.mp3");
            tom4.play();
            break;
        case 'j':
            var snare = new Audio("sounds/snare.mp3");
            snare.play();
            break;
        case 'k':
            var crash = new Audio("sounds/crash.mp3");
            crash.play();
            break;
        case 'l':
            var kick = new Audio("sounds/kick-bass.mp3");
            kick.play();
            break;
        default:
            console.log("key was pressed");
    }
}


function buttonAnimation(buttonKey)
{
    var activeButton = document.querySelector("."+buttonKey);
    activeButton.classList.add("pressed");
    setTimeout(function(){
        activeButton.classList.remove("pressed");
    },100);
}