JS Runs sections of code inside a if statement when conditions are not met

I have this section of code that every 10 seconds it checks if the player has enough Xp to level up if they do it will add 1 to there level, double the neededXp and rest there Xp to 0.

but for some reason every 10 seconds it doubles needed Xp even when i don't have enough Xp it doesn't do any of the other things though. Also level up does work. (if i can get enough XP quick enough before it doubles its way to a large number)

window.setInterval(
function levelup() {
if (Xp >= neededXP)
    level = level + 1;
    neededXP = neededXP * 2;
    Xp = 0;
    document.getElementById("level").innerHTML = level
    document.getElementById("neededXP").innerHTML = neededXP
               document.getElementById("Xp").innerHTML = Xp
               }, 10000);