ceiling
This function returns the smallest integral value that is not less than x.
double ceiling(double x)
Parameters:
x
The number to round.
Return value:
The smallest integral value that is not less than x.
Remarks:
This function will always increase x, except where x is already an integer. For example, the ceiling of 5.1 will be 6, but the ceiling of -5.1 will be -5.
Example:

    void main()
    {
    alert("ceiling test", "ceiling of 5.1 is "+ceiling(5.1)+".");
    alert("ceiling test", "ceiling of 5 is "+ceiling(5)+".");
    alert("ceiling test", "ceiling of -5.1 is "+ceiling(-5.1)+".");
    }