createCanvas(400, 400);

}

​

function draw() {

  background(220);

  noFill();

  // a for loop has three parts

  // 1 - INITALIZATION

  // declaration of a variable (usually is i)

  // 2 - TESTING STATEMENT

  // statement which tests the variable at each loop

  // 3 - UPDATING VARIABLE

  // updating the value of i at each loop

  for( let i = 0 ; i < width ; i = i + 30){

​

    // this will be evaluated as long as the statement is true

    fill(i / 2);

    circle(width/2,height/2, width - i);

​

  }

}

​

​