Question

I know this may be an easy answer, but I am having trouble using my function with setInterval. Here is what I have so far:

function countUp(n) {
     console.log(n++);
}

setInterval( function() { countUp(10); }, 1000);

If I move my variable outside the function and increment that value, it will work. However, I want to be able to set the number to anything when I call the function countUp. The above code just keeps logging 10.

EDIT:

Is there any way to pass an argument to this function and make it work with setInterval without having to declare a global variable?

Answer 1

You need to increment a variable in the enclosing scope of the function:

var n = 10;

function countUp() {
    console.log(n++);
}

setInterval(countUp, 1000);

Update: Here’s a strategy that doesn’t involve a global variable:

function countUp(start) {
    return function() {
        console.log(start++)
    }
}
setInterval(countUp(10), 1000);

As I noted, the counter just needs to be in the enclosing scope, not the global scope. So passing it into a function that can reference it in a closure will work fine here.