Random number generator without dupes in Javascript?

Question

I need help with writing some code that will create a random number from an array of 12 numbers and print it 9 times without dupes. This has been tough for me to accomplish.

Answer 1

The most effective and efficient way to do this is to shuffle your numbers then print the first nine of them. Use a good shuffle algorithm.What Thilo suggested will give you poor results. See here.

Edit Here's a brief Knuth Shuffle algorithm example:

void shuffle(vector nums)
{
  for (int i = nums.size()-1; i >= 0; i--)
  {
    // this line is really shorthand, but gets the point across, I hope.
    swap(nums[i],nums[rand()%i]);
  }
}