frameCount()
A Number variable that tracks the number of frames drawn since the sketch started.
frameCount's value is 0 inside setup(). It increments by 1 each time the code in draw() finishes executing.
Examples

function setup()
size(100, 100)
background(200)
-- Display the value of
-- frameCount.
textSize(30)
textAlign(CENTER, CENTER)
fill(0)
text(frameCount, 50, 50)
describe('The number 0 written in black in the middle of a gray square.')
end

function setup()
size(100, 100)
-- Set the frameRate to 30.
frameRate(30)
textSize(30)
textAlign(CENTER, CENTER)
describe('A number written in the middle of a gray square. Its value increases rapidly.')
end
function draw()
background(200)
-- Display the value of
-- frameCount.
text(frameCount, 50, 50)
end