index.js

for(let i=0 ; i<document.querySelectorAll(".drum").length ; i++){
    document.querySelectorAll(".drum")[i].addEventListener("click" , function(){
        var pressedKey  = this.innerHTML;
        makeSound(pressedKey);
        buttonAnimation(pressedKey);
    })
}

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


function buttonAnimation(currentKey){
    var activeButton = document.querySelector("."+currentKey);
    activeButton.classList.add("pressed");

    setTimeout(function(){
        activeButton.classList.remove("pressed");
    },100);
}