You can use a forEach like you intended if you modify the array initialization to be:
var arr = Array.apply(null, Array(10))
And then you can do a foreach like:
arr.forEach(function(el, index) {
arr[index] = 0;
});
The result is:
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]