Fibonacci method

fibb.rb

index = ARGV[0].to_i
def fibb(times)
start = [0]
  times.times do |x|
    if x.zero?
      start << 1
    else
      start << start[x -1] + start[x]
    end
  end
  print start[times -1]
end

fibb(index)

James Logan solution, in JS

function fib (index){
  var seq = [0,1];
  while(seq.length < index+1) {
    seq[seq.length] = (seq[seq.length-1]) + (seq[seq.length -2]);
  }
  return seq[index]
}