index.js

let cards;
let sum=0;
let hasBlackJack = false;
let isAlive = false;
let message = "";
let messageEl = document.getElementById("message-el");
let sumEl = document.getElementById("sum-el");
let cardsEl = document.getElementById("cards-el");

let player = {
    name:"Per",
    chips: 145
}

let playerEl = document.getElementById("player-el");
playerEl.textContent = player.name + " : $" + player.chips;

function getRandomCard(){
    let ranNum = Math.floor(Math.random()*13)+1;
    if(ranNum>=10){
        return 10;
    }
    else if(ranNum===1){
        return 11;
    }
    else{
        return ranNum;
    }
}

function startGame(){
    let firstCard = getRandomCard();
    let secondCard = getRandomCard();
    sum = firstCard + secondCard;
    cards = [firstCard,secondCard];
    isAlive = true;
    hasBlackJack = false;
    renderGame();
}

function renderGame(){
    cardsEl.textContent = 'Cards : ';
    for(let i=0 ; i<cards.length ; i++)
    {
        cardsEl.textContent +=cards[i]+' ';
    }
    sumEl.textContent = "Sum : " + sum;
    if(sum <= 20){
        message = "Do you want to draw a new card?";
    }else if(sum === 21){
        message = "You've got Blackjack!";
        hasBlackJack = true;
    }else{
        message = "You're out of the game!";
        isAlive = false;
    }
    messageEl.textContent = message;
}

function newCard(){
    if(hasBlackJack===false && isAlive===true){
        let card = getRandomCard();
        sum += card;
        cards.push(card);
        renderGame();
    }
}