select random value NOT in array

Question

How would I select a random value (0 to 30) that is not in this array?

var list = new Array(1,3,4,7,8,9);

Answer 1

function RandomValueNotInArray(array)
{
    var e;
    do
    {
        e = Math.random() * 31; // n + 1
    } while (array.contains(e))
    return e;
}