randomSelectSomeFromTotal

fuction randomSelectSomeFromTotal(some, total) {
    var a = new Array();
    var b = new Array();
    for (var i = 0; i < total; i++) a[i] = i;
    for (var j, x, i = a.length; i; j = parseInt(Math.random() * i), x = a[--i], a[i] = a[j], a[j] = x);
    for (var i = 0; i < some; i++) b[i] = a[i];
    return b.sort(function(a, b) {
        return a - b
    });
}