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

There are many ways to solve this problem, the following is my suggestion:

function onloadFunctions() {
    var count = 0;
    var delta = 1;
    var target = document.getElementById("here");
    var step = function() {
        if(count <= 0) delta =  1;
        if(count >= 9) delta = -1;
        count += delta;
        target.innerHTML = count;
        window.setTimeout(step, 500);
    }
    step ();
}

PS: it's safer to use setTimeout than setInteval.