How do I correctly use setInterval and clearInterval to switch between two different functions?

Question

For practice I am trying to display a number that increments from 0 - 9, then decrements from 9 - 0, and infinitely repeats.

The code that I have so far seems to

Answer 1

clearInterval(this);. You can't do that. You need to save the return value from setInterval.

var interval;
function onloadFunctions()
{
    countUp();
    interval = setInterval(countUp, 200);
}

var count = 0;
function countUp()
{
    document.getElementById("here").innerHTML = count;
    count++;

    if(count == 10)
    {
        clearInterval(interval);
        countDown();
        interval = setInterval(countDown, 200);
    }
}
function countDown()
{
    document.getElementById("here").innerHTML = count;
    count--;

    if(count == 0)
    {
        clearInterval(interval);
        countUp();
        interval = setInterval(countUp, 200);
    }       
}