/*
 *@name Functions
 *@description The drawTarget() function makes it easy to draw many distinct 
 *targets. Each call to drawTarget() specifies the position, size, and number of
 *rings for each target.
*/

function setup() {
  createCanvas(720, 400);
  background(51);
  noStroke();
  noLoop();
}

function draw() {
  drawTarget(width*0.25, height*0.4, 200, 4);
  drawTarget(width*0.5, height*0.5, 300, 10);
  drawTarget(width*0.75, height*0.3, 120, 6);
}

function drawTarget(xloc, yloc, size, num) {
  grayvalues = 255/num;
  steps = size/num;
  for (i = 0; i < num; i++) {
    fill(i*grayvalues);
    ellipse(xloc, yloc, size - i*steps, size - i*steps);
  }
}
/*
 *@name Functions
 *@description The drawTarget() function makes it easy to draw many distinct 
 *targets. Each call to drawTarget() specifies the position, size, and number of
 *rings for each target.
*/

function setup() {
  createCanvas(720, 400);
  background(51);
  noStroke();
  noLoop();
}

function draw() {
  drawTarget(width*0.25, height*0.4, 200, 4);
  drawTarget(width*0.5, height*0.5, 300, 10);
  drawTarget(width*0.75, height*0.3, 120, 6);
}

function drawTarget(xloc, yloc, size, num) {
  var grayvalues = 255/num;
  var steps = size/num;
  for (var i = 0; i < num; i++) {
    fill(i*grayvalues);
    ellipse(xloc, yloc, size - i*steps, size - i*steps);
  }
}

Update 06_Functions.js