How can I make the rgb a rainbow like those fancy chairs?

I tried using variables but that didnt work, the code is
init = function() r=0 b=0 g=0 end

draw=function() screen.clear() screen.setAlpha(1) r=r+1 g=g+2 b=b+3 screen.fillRect(0,0,200,80, "rgb(r, g, b)") if r == 255 then r=0 end if g == 254 then g=0 end if b==255 then b=0 end end

and the colours of the box don't change, it is very annoying >:(

Okay, it doesn't work because you don't have the function that mixes colors. Try this code.

init = function()
  time = 2
  r = random.next() * 255
  g = random.next() * 255
  b = random.next() * 255
  width = 30
  height = 30
end

update = function()
  time = time - 1/60
  
  if time <= 0 then
    r = random.next() * 255
    g = random.next() * 255
    b = random.next() * 255
    time = 2 
  end
  
  width = 30 + cos(system.time() / 100) * 10
  height = 30 + sin(system.time() / 100) * 10
end

draw = function()
  screen.clear()
  screen.fillRect(0, 0, width, height, "rgb(" + r + "," + g + "," + b + ")")
  screen.drawText("multicolor square", 0, -50, 15, "white")
end