x:0,

  y:0

};

var col = {

  r:0,

  g:0,

  b:0

};

​

function setup() {

  createCanvas(600, 400); //width, height

  background(0);

}

​

function draw() {

  dot.x = random(0,width); //width variable to get the canvas width

  dot.y = random(0,height); 

  col.r = random(100,255);

  col.b = random(100,190);

  fill(col.r, col.g, col.b, 100); //Opacity 255 means 100% Opaque which is the default value, lesser the value more transparent is the color.

  noStroke();

  ellipse(dot.x, dot.y, 25, 25);

}