Javascript beginner while loops

I am new to programming and i tried to code a little game in JavaScript. I stucked on while loops, I'm not getting any errors but somehow they're not working as I want. I'm adding code below:

window.alert("Troll has 20 health, you have 10");
var user = prompt("How you want to beat troll, sword, bow or spear").toLowerCase();
var fight = true;
var atkdamage = Math.floor(Math.random() * 5);
var totaldamage = 0;
var totaldamagercv = 0;
switch (user)  {
case 'sword':
    window.alert("cool choice, let's start..");
    while (totaldamage < 20)   {
        window.alert("You hit " + atkdamage);
        window.alert("Troll has " + (20 - atkdamage) + "health left");
        totaldamage += atkdamage
        window.alert("TOTAL DAMAGE" + totaldamage);
    }
    if (totaldamage >= 20)
    {
        window.alert("You win.");
    }
    break;
case 'bow':
    window.alert("coward but effective, let's start..");
    while (totaldamage < 20)   {
        window.alert("You hit " + atkdamage);
        window.alert("Troll has " + (20 - atkdamage) + "health left");
        totaldamage += atkdamage
    }
        if (totaldamage >= 20)
    {
        window.alert("You win.");
    }
    break;
case 'spear':
    window.alert("smart choice, let's start..");
    while (totaldamage < 20)   {
        window.alert("You hit " + atkdamage);
        window.alert("Troll has " + (20 - atkdamage) + "health left");
        totaldamage += atkdamage
    }
if (totaldamage >= 20)
    {
        window.alert("You win.");
    }
    break;
default:
window.alert("what?");
}

Could you please answer which part of the code is wrong?

Thank you very much.