let y;

function setup() {

 createCanvas(400, 400);

 x = 200;

 y = 200;

 background(0,0,0);

 for (let i = 0; i < 100000; i++) {

   draw();

 }

}

function draw() {

 //background(220);

 stroke(random(255),random(255),random(255));

 strokeWeight(5);

 let randomValue = random();

 if (randomValue < 0.25) {

     x-=5; // x -= 1

 }

 else if (randomValue < 0.5) {

     x+=5; // x += 1

 }

 else if (randomValue < 0.75) {

     y-=5;

 }

 else {

     y+=5;

 }

 point(x, y);

 if (x > 400) {

   x = 200

 }

 if (y > 400) {

   y = 200;

 }

}