Why isn't my global variable available within my function?

Question

When you run a script, I noticed the variables you write out get run only once. Functions on the other hand, can be called multiple times.

Is there a way to call up a variable more than once like you can functions? Sorry no code for this one, just a question.

Edit: To clarify, I have a global variable that is used for a function. However when I try to call this variable from a seperate function, it does not register because it is now considered "local".

However, if I could call up the global variable at will, then I believe this would fix the issue.

// BLITZ SKILL  // <-- My 2nd Function trying to use my global variable counter
document.getElementById("blitz").addEventListener('click', function(){
    var counter = setInterval(timer, 1000); // Trying to restart timer, does 
                                            // not register counter variable.
    var damage = Math.floor(Math.random() * characterstats.strength);
    document.getElementById("energy").innerHTML = character.energy;

    if ((damage <= 0) && (character.energy >= 5)) {
        addMessage("You miss the dragon!");
        character.energy -= 5;
    }

    else if (character.energy <= 4) {
        addMessage("Not enough energy!")
    }

    if ((damage >= 1) && (character.energy >= 5)) { 
        dragon.hp -= damage;
        document.getElementById("npchp").innerHTML = dragon.hp;
        addMessage("You hit the dragon for " + damage + " hp!");
        character.energy -= 5;
    }
    document.getElementById("energy").innerHTML = character.energy;
});

// 7. CODE TESTING AREA
var counter = setInterval(timer, 1000);  <-- MyGlobal Variable

function timer() {  //
    var count = character.energy;
    count += characterstats.energyregen;
    if (count >= 35) {
        clearInterval(counter);
    }
    document.getElementById("energy").innerHTML = count;
    character.energy = count;
}

Answer 1

You are creating a new local variable called counter in your function by using var.

Just reference the global like so without using "var" which defines a new variable,

document.getElementById("blitz").addEventListener('click', function(){
    counter = setInterval(timer, 1000); // <-- Trying to restart timer, does not
    ...