How to increment/decrement variable value only once while in a loop?

Question

I need to decrement var "left" by 1 and only once instead of having it go through a loop and decrement if conditions pass true. But conditions are valid only if they are in a loop. How would I do this?

 let key = e.key.toLowerCase()
    for (i = 0; i < word.length; i++) {
        if (word[i] == key) {
            if (guessed[i] != key) {
                console.log(e.key)
                guessed[i] = key
            } else {
                console.log('This is where i want left--')
            }
        }
    }
    left--;  //Need this to decrement only once

Answer 1

Store whether left has been decremented in a variable:

let key = e.key.toLowerCase()
let decrementedLeft = false;
for (i = 0; i < word.length; i++) {
    if (word[i] == key) {
        if (guessed[i] != key) {
            console.log(e.key)
            guessed[i] = key
        } else {
            if(!decrementedLeft){
                decrementedLeft = true;
                left--;
            }
        }
    }
}
if(!decrementedLeft){
    left--;
}