createCanvas(700, 400);

    background(255);

    rectMode(CENTER);

}

​

function draw(){

    // the modulo operator % calculates the remainder.

    // example: 24 % 25 = 24, 25 % 25 = 0, 26 % 25 = 1, etc.

    // this if statement will evaluate True every 25 frames.

    if (frameCount % 25 == 0) {

        fill(random(255), random(255), random(255));

        push();

        translate(200, 200);

        rotate(radians(frameCount));

        rect(0, 0, 400, 20);

        pop();

    }

}