var yPos = [];

//100,200,300, 20,80,10

​

function setup() {

  createCanvas(400, 400);

  count = 0; 

  while(count < 1000){

  append(xPos,random(400));

  append(yPos,random(400));

    count++;

  }

  noStroke();

  background(0);

}

​

function draw() {

  background(0,0,0,10);

  var i = 0

  while(i < xPos.length){

    ellipse(xPos[i],yPos[i],5,5);

    fill(0,0,255);

    //30

    yPos[i]++;

    if(yPos[i] > 400){

      yPos[i] = 0;

    }

    i++; //same as i = i + 1;

  }

}