CODEWITHSUNDEEP
javascripthtml
tmanrocks994
tmanrocks994

Reputation: 139

How to prevent my mana value from going negative

So when I use my skill it takes 10 mana from mana total then adds 50 to cookie total but if I use the skill again it keeps taking mana. i have it set so cookies does not increase but my mana keeps going down. how do i prevent values from going negative.

I haven't tried much not sure how to prevent it

This is my Javascript code:

function Bigclick() {
        if (ManaPoints >= 10)
        if (rebirths >=1)    
        cookies = cookies + 50
        ManaPoints = ManaPoints - 10;
        document.getElementById('cookies').innerHTML = cookies;
        document.getElementById("ManaPoints").innerHTML = ManaPoints;
        checkCursor()
}

I expect If im below 10 mana or at 0 mana for the function to not do anything. but the actual output the Mana keeps going down http://prntscr.com/ns2d0m

Upvotes: 0

Views: 37

Answers (2)

DontVoteMeDown
DontVoteMeDown

Reputation: 21465

Those ifs only works for cookies = cookies + 50. You need to open a block and wrap all calculations that depends on those conditions, e.g.:

function Bigclick() {
    if (ManaPoints >= 10 && rebirths >=1) {
        cookies = cookies + 50
        ManaPoints = ManaPoints - 10;
        document.getElementById('cookies').innerHTML = cookies;
        document.getElementById("ManaPoints").innerHTML = ManaPoints;
    }
    checkCursor()
}

Not sure if the code above is exactly what you need, it is just an example.

Another example of how your conditions were woring initially:

var truthy = false;

if (truthy)
if (!!truthy)
console.log("truthy");
console.log("not truthy");

UPDATE:

let button = document.getElementById("use-mana"),
    manaQty = document.getElementById("mana-qty");
    
const manaCost = 10;
    
button.addEventListener("click", () =>
{
  let qty = Number(manaQty.innerText);
  
  if (qty >= manaCost)
  {
    qty-= manaCost;
    manaQty.innerText = qty;
  }
  else 
  {
    window.alert("Not enough mana!");
  }
});
<div id="mana-qty">29</div>
<button id="use-mana">Use Mana</button>

Upvotes: 3

obscure
obscure

Reputation: 12891

Generally - if you want to avoid a number becoming negative after subtraction - you have to check if it would be smaller than 0 if you subtract a specific value. If it does make it zero, if it doesn't subtract the desired amount.

if (ManaPoints - 10 < 0) {
  ManaPoints = 0;
} else {
  ManaPoints -= 10;
}

Upvotes: 1

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