// tweakable vars
var delay = 1000;             // milliseconds
var changeSpeedOverTime = 1;  // 0 == no, 1 == speed up, -1 == slow down
var changeAmount = 10;        // milliseconds
var maxSpeed = 500;           // if speeding up, go no faster than this

// array of spans to change.
// Value is the number of random numbers to generate.
// Array position + 1 is the span id.
var spans = [ 2, 6, 8, 14 ];

// don't change me
var d = document;

function setup()
{
    for ( i = 0; i < spans.length; i++ ) {
        var span = i + 1
        setTimeout("scheduleRand("+ spans[i] +","+ span +")", delay); 
    }
    return;
}

function scheduleRand(num, span)
{
    text = d.getElementById( span );
    if ( ! text ) return;

    if ( changeSpeedOverTime == -1 ) {
       delay = delay + changeAmount;
    }
    else if ( changeSpeedOverTime == 1 ) {
       delay = delay - changeAmount;
       if ( delay < maxSpeed ) delay = maxSpeed;
    }

    text.innerHTML = makeRand(num);
    setTimeout("scheduleRand("+ num +","+ span +")", delay); 
    return;
}

function makeRand(num)
{
    var ret;
    for( i = 0; i < num; i++ ) {
        var rand = Math.floor( Math.random() * 10 );
        ret = ret ? ret + String(rand) : String(rand);
    }  
    return ret;
}