game.js

var buttonColours = ["red", "blue", "green", "yellow"];
var gamePattern = [];
var userClickedPattern = [];
var first = false;
var level = 0;
$(document).keypress(function(){
  if(first === false){
    $("h1").text("Level "+level);
    nextSequence();
    first = true;
  }

});

$(".btn").click(function(){
  var userChosenColour = this.id;
  userClickedPattern.push(userChosenColour);
  playSound(userChosenColour);
  animatePress(userChosenColour);
  checkAnswer(userClickedPattern.length-1);
  // console.log(userClickedPattern);
});

function nextSequence(){
  level++;
  $("h1").text("Level "+level);
  userClickedPattern = [];
  var randomNumber = Math.floor(Math.random()*4);
  var randomChosenColour = buttonColours[randomNumber];
  gamePattern.push(randomChosenColour);
  $("#"+randomChosenColour).fadeOut(100).fadeIn(100);
  playSound(randomChosenColour);
}

function playSound(name){
  var audio = new Audio("sounds/"+name+".mp3");
  audio.play();
}

function animatePress(currentColour){
  $("#"+currentColour).addClass("pressed");
  setTimeout(function(){
    $("#"+currentColour).removeClass("pressed");
  }, 100);
}

function checkAnswer(currentLevel){
  if(userClickedPattern[currentLevel] === gamePattern[currentLevel]){
    if(userClickedPattern.length === gamePattern.length){
      setTimeout(function(){
        nextSequence();
      },1000);
    }
  }
  else{
    playSound("wrong");
    $("body").addClass("game-over");
    setTimeout(function(){
      $("body").removeClass("game-over");
    }, 200);
    $("h1").text("Game Over, Press Any Key to Restart");
    startOver();
  }
}

function startOver(){
  level = 0;
  gamePattern = [];
  first = false;
}