index.js

//Detecting Button Press
for (var i = 0; i<document.querySelectorAll(".drum").length; i++) {
    document.querySelectorAll(".drum")[i].addEventListener("click", function () {
        
        var buttonInnerHTML = this.innerHTML;

        makeSound(buttonInnerHTML);

        buttonAnimation(buttonInnerHTML);
       //What to do when click deteted.
    });
}

//Detecting Keyboard Press

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

//Making Sounds
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(buttonInerHTML);
    }  
}


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

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